TA 

aso 


UC-NRLF 


277    D7M 


O 

o 


Y       ~     L 


J         -MT  -LIBRARY 

OF    THE 

UNIVERSITY   OF   CALIFORNIA 

GIRT  OR 


Received '._..       ... 
Accessions  No. 3^ ^33          Shelf  No. 


RAILWAY  MASONRY 


AND 


BRIDGE    FOUNDATIONS, 


BY 

JAMES    HASLEY, 

MASTER  MASON  LITTLE  ROCK  &  FORT  SMITH  RAILWAY. 


CHICAGO: 

THE   RAILWAY   AGE  PUBLISHING  CO. 
1883. 


DEDICATORY. 


To  THEODORE    HARTMAN,    of    the    Little    Rock  &  Fort 

Smith  railway,   to   whom  I  owe  my  sincere   thanks   for  many 

acts  of  unostentatious    kindness,    doubly    appreciated  when 

conferred  by  an    employer    upon     his    employe,     this  little 

work    is  respectfully    dedicated,   with  the   regret    that  it    is 
not  more  worthy,       ^,7/^3  3 
By  the  author, 

JAMES  HASLET. 


ON  THE  ROAD: 

December  1,  1882. 


OOIVTE7VTS. 


CHAPTER  I.  '                                PAGE. 
Introduction 5. 

CHAPTER  II. 
Various  kind  of  stone. — Styles  of  masonry 8 

CHAPTER  III. 
Various  styles  of  dressing. — Pointing  joints 15 

CHAPTER  IV. 
The  foundations 19 

CHAPTER  V. 
Manner  of  construction. — Abutments 29 

CHAPTER  VI. 
Box  and  arch  culverts 34 

CHAPTER  VII. 
Hydraulic  foundations 40 

CHAPTER  VIII. 
Concrete  work 57 

CHAPTER  IX. 
Protection  against  scour 62 


RAILWAY    MASONRY 


CHAPTER  I. 

INTRODUCTION. 

I  propose  in  this  little  work  to  treat  upon  the  subject  of  rail- 
way masonrj ,  devoting  attention  more  particularly  to  the  foun- 
dations and  masonry  of  heavy  bridge  work,  but  by  no  meaus 
ignoring  those  works  of  lesser  magnitude  known  as  culverts. 
With  no  impracticable  theories  to  advance,  no  costly  experi- 
ments to  advocate,  I  shall  on  the  contrary  merely  offer  such  re- 
marks and  suggestions  as  are  based  upon  the  actual  experience 
of  several  years  as  working  mason  and  foreman  in  all  classes  of 
general  railway  work  in  stone,  brick  and  concrete,  with  the  hope 
that  such  experience  may  prove  valuable  to  those  who  may  be 
interested  in  the  matter. 

No  one  can  with  propriety  question  the  great  superiority  of  well 
constructed  masonry,  over  structures  of  wood,  not  only  in  point 
of  solidity  and  permanence,  but  also  of  economy  in  the  long  run. 
Well  constructed  masonry  should  never  require  repairs,  never 
need  renewing.  Its  first  cost  should  be  its  only  cost.  Though 
superstructures  should  decay  and  drift  away,  though  embank- 
ments should  crumble  and  wash  out,  masonry  should  stand  as 
one  great  mass  of  solid  rock,  firm  and  enduring. 


O  RAILWAY    MASONRY 

Several  items  require  especial  attention  in  the  construction  of 
masonry  for  water  ways,  to  render  it  permanent  and  of  value. 
Thevare: 

1.  The  selection  of  stone  of  proper  quality,  which  will   not 
soften  or  decompose,  crack  or  scale  off  from  exposure  either  to 
air  or  water. 

2.  Proper  dressing  of  the  stone  to  true  and  level  beds  and 
reasonable  joints. 

3.  The  use  of  mortars  composed  of  proper  materials  in  proper 
proportions  and  thoroughly  incorporated  with  each  other. 

4.  Firm  and  solid  foundations,  with  the  footings  at  such  depth 
as  will  cause  no  danger  from  the  scouring  action  of   the  current. 

5.  Conscientious  and  thorough  workmanship. 

Some  roadmaster,  recently  from  the  scene  of  a  disastrous  and 
expensive  washed-out  culvert  may  suggest  another  item, — that  of 
"  Sufficient  width  of  opening."  But  that  in  my  opinion  is  en- 
tirely a  matter  of  judgment.  The  stream  at  its  ordinary  stage 
may  appear  so  trivial  and  insignificant  as  to  require  but  a  narrow 
opening  way.  After  excessive  rainfall  the  same  stream  may 
rise  rapidly  and  swell  to  considerable  proportions,  carrying  a 
large  volume  of  water  which  not  finding  ample  outlet  sweeps 
away  the  superstructure  and  washes  out  the  roadbed.  But  if 
the  masonry  is  constructed  with  due  regard  to  the  above  enum- 
erated items  the  abutments  and  piers  will  remain  uninjured 
and  intact.  Therefore  the  disaster  could  not  be  attributed  to  the 
masonry,  as  the  same  would  have  occurred  in  the  case  of  a  tim- 
bered culvert  with  only  equal  width  of  water  way,  with  the 
great  probability  that  unless  well  piled  and  very  strongly  built 
the  entire  wood  work,  with  considerable  of  the  embankment, 
would  have  washed  out  and  away. 

The  width  of  opening,  therefore,  is  foreign  to  the  subject  of 


RAILWAY     MASONRY.  7 

masonry,  although  intimately  related  to  it,  and  deserving  consid- 
erable thought,  observation  and  judgment.  Ample  provision 
should  be  made  for  the  passage  of  unusually  large  quantities  of 
water,  although  it  might  not  be  required  one  time  in  many 
years. 


RAILWAY    MASONRY. 


CHAPTER  II. 

VARIOUS  KINDS  OF   STONE — STYLES  OF   MASONRY. 

The  first  point  to  be  observed  in  the  building  of  masonry  is 
the  kind  and  quality  of  the  stone.  For  bridge  work  granite  is, 
beyond  all  doubt,  the  most  beautiful  and  durable.  Although  of 
several  different  colors  and  of  varied  granulation  still  it  is  almost 
uniformly  of  the  same  weight  and  crushing  resistance.  This  stone 
being  found  in  large  masses  and  unstratified,  in  addition  to  its 
great  hardness,  renders  it  a  very  costly  stone  to  quarry  and  dress. 
I  have  never  seen  but  one  lot  of  inferior  granite,  and  that  was 
due  to  the  excessive  presence  of  mica. 

Most  of  the  limestones  are  very  suitable  for  pier  and  abutment 
work.  They  occur  in  layers  of  various  thickness,  the  stone  be- 
ing very  close  grained  and  dressing  freely.  The  blue  limestone 
is  very  dense  and  weighs  about  the  same  as  granite,  which  is  165 
pounds  to  the  cubic  foot.  The  white  and  magnesian  limestones 
are  not  so  heavy,  and  when  quarried  are  quite  soft,  more  espe- 
cially the  magnesian,  which  can  be  cut  with  an  ordinary  pen  knife, 
the  same  as  chalk.  Exposure  to  the  air  hardens  either  variety 
and  they  answer  quite  satisfactorily  for  railway  work.  Some 
limestones,  however,  have  a  tendency  to  slake  and  decompose  on 
exposure  to  the  air  and  water. 

Another  very  fine  stone,  which  is  rarely  found  imperfect  and 
which  preserves  its  integrity  throughout,  is  the  basalt  or  blue  flag- 
stone. It,  too,  Is  a  stratified  stone,  with  nearly  level  beds.  It 
splits  and  works  very  freely  in  the  direction  with  its  grain,  but  ia 
exceedingly  difficult  to  work  satisfactorily  transversely.  It  is  ex- 


RAILWAY    MASONRY.  9 

tremely  heavy,  weighing  about  170  pounds  to  the  cubic  foot,  and 
can  bear  much  greater  transverse  strain  than  any  other  variety 
of  stone.  The  smoothness  of  its  beds  and  its  great  strength 
have  rendered  it  the  favorite  for  flagging,  curbing  and  covering 
of  vaults  and  box  culverts.  Upon  the  line  of  the  Little  Rock  & 
Fort  Smith  railway  there  is  a  very  fine  quarry  of  this  stone  in 
layers  varying  from  three  inches  up  to  nine  and  ten.  At  one 
point  a  nine-inch  layer  is  uncovered  disclosing  one  perfect  stone 
19  teet  in  length  by  7  feet  in  width,  and  many  others  nearly  as 
large. 

At  Mill  Creek  the  company  have  a  quarry  of  the  same  stone 
existing  in  heavier  layers.  I  have  used  many  blocks  of  stone 
from  this  quarry  measuring  seven  and  eight  feet  in  length  by 
two  to  three  wide,  and  from  two  to  two  and  a  half  in  height, 
weighing  from  four  to  five  tons  each.  I  have  split  this  stone 
lengthwise  from  fifteen  to  twenty  feet  with  one  ounce  of  powder. 
Fortunately  I  was  located  on  the  hillside  above  the  track,  and 
simply  snubbed  it  down  the  bill  with  a  rope  and  levers  onto  the 
cars.  At  the  work  I  drag  it  in  on  skids  and  rollers  operated  by  a 
crab  and  rope.  However,  this  is  off  the  subject,  only  serving  to 
fehow  at  what  little  cost  work  can  be  done  with  such  stone. 

Sandstone  is  the  only  class  which  requires  the  exercise  of 
much  judgment  and  caution.  It  is  so  varied  in  character, 
its  ingreuients  are  so  diversified  and  so  dissimilarly  incorporated, 
its  texture  and  weight  are  so  unlike,  that  considerable  inquiry  is 
needed  to  make  sure  that  it  is  suitable  for  railway  work.  Sand- 
stone is  nothing  more  nor  less  than  sand  agglutinated  or  con- 
creted with  soil  and  mineral  substances,  such  as  mica,  iron,  clay, 
loam,  ochre,  marl,  etc.,  etc.,  in  hap-hazard  proportions,  and  its 
worth  as  building  material  is  as  variable  as  are  the  ingredients 
which  compose  it. 


10  RAILWAY     MASONRY. 

All  sandstone  hardens  to  a  greater  or  less  extent  upon  exposure 
to  the  atmosphere,  although  nearly  all  that  is  of  large  coarse 
grain  and  excessive  earthly  matter  will  even  then  be  so  weak  and 
friable  as  to  be  unfit  for  use  on  account  of  the  scaling  off  and 
crumbling  away  of  the  particles. 

Sandstone  is  of  various  colors  and  shades  (which  become  very 
dingy  in  course  of  time)  and  exists  in  the  form  of  boulders  and 
also  in  slratas  or  ledges.  It  can  sustain  but  little  strain  across 
its  grain,  i.  e.  transversely.  In  weight  it  varies  from  100  to  130 
pounds  to  the  cubic  foot  and  is  by  far  the  easiest  and  cheapest 
stone  to  quarry  and  dress. 

The  next  point  to  be  observed  is  the  proper  dressing  of  the 
stone  to  true  and  level  beds  and  also  close  }oints,  if  first  quality 


ORDINARY  .HUBBLE,   WITH  DRESSED  QUOIN. 

work  is  desired.  I  have  seen  some  very  stable  work  put  up  of 
only  the  ordinary  "  rubble,"  (see  illustration)  without  any 
dressing  except  of  adraft  on  the  quoins  by  which  to  plumb  the 


RAILWAY     MASONRY. 


11 


corners  and  carry  them  up  neatly.  A  few  strokes  of  the  hammer 
were  alsp  necessary  occasionally  to  spall  off  any  projections  or 
surplus  stone.  But  this  style  of  work  is  not  generally  advisable, 
as  very  few  mechanics  could  be  relied  upon  to  take  the  proper 
amount  of  care  in  spalling  and  leveling  up  the  beds  and  filling 
the  ragged  joints  of  such  work.  As  a  consequence  one  small 
stone  may  jar  loose  and  fall  out,  resulting  probably  in  the 
downfall  of  a  considerable  part  of  the  abutment.  However,  as 
most  bridge  masonry  is  far  more  expensive  and  massive  than  is 
generally  required,  I  shall  again  allude  to  this  class  of  work  under 
the  head  of  "  workmanship." 

Another  style  of  cheap  work  is  that  known  as  "  broken  ashlar" 
and    "bond    rubble"  or  "rubble  range  work".     The  broken 


CT^^ 


BROKEN  ASHLAR,  OR  RUBBLE  RANGE  WORK. 

ashiar  is  a  dressed  stone,  but  instead  of  every  stone  in  the 
course  being  of  the  same  height,  ,it  is  admissible  to  use  some  of 
the  proper  height  of  the  course  and  also  some  not  of  the  proper 


12 


RAILWAY     MASONRY. 


height,  but  which  must  be  brought  up  to  the  level  of  the  others 
by  building  more  upon  them.  Bond  rubble,  or  rubble  range  work 
is  built  upon  the  same  style,  only  of  undressed  stone,  for  which 
the  stratified  stones  are  eminently  suitable.  Any  protuberances 
upon  the  beds  are  axed  off  and  a  very  ragged  joint  may  be  roughly 
hammer-dressed.  All  of  the  stratified  stones  can  be  laid  very 
economically  and  to  good  effect,  either  in  broken  or  unbroken 
courses. 

Some  of  these  naturally  bedded  stones  are  so  smooth  and  uni- 
form as  to  need  no  dressing  or  spalling  up.  In  such  case  no 
further  search  for  stone  is  necessary,  and  a  great  expense  for  cut- 
ting is  saved  and  strong  massive  work  is  ensured. 


CUT  ASHLAR,  WITH  PLAIN  FACE  AND  EDGES. 

But  the  majority  of  these  ready  bedded  stones  have  more  or 
less  inequalities,  and  iu  order  to  keep  them  level  in  the  course  it 
becomes  necessary  to  raise  them  up.  perhaps  at  one  corner,  per 


RAILWAY     MASONRY. 


13 


haps  at  another  or  both,  as  the  case  may  be,  by  placing  a  chip  or 
chips  of  stone,  called  spalls,  under  the  bed,  and  slushing  the  va- 
cant spaces  well  and  full  with  mortar.  And  it  is  just  here  that 
the  disadvantage  of  this  style  of  work  becomes  apparent.  Unless 
the  mason  distributes  these  spalls  under  the  stone  so  that  it  sets 
firmly  and  does  not  rock, — unless  these  spalls  are  placed  so  that 
all  parts  of  the  stone  sustained  by  them  distribute  their  weight 
and  pressure  equally,  such  stone  will  in  all  probability  become 
ruptured  and  split,  and  a  few  such  instances  in  the  same  work 
may  occasion  considerable  disaster.  But  with  proper  care  such 
class  of  work  under  ordinary  conditions  proves  to  be  all  that  is 
needed,  and  if  neatly  jointed  with  good  cement  mortar  will  also 
appear  to  good  advantage. 


PITCHED  FACED  ASHLAR. 

The  more  expensive  and  generally  preferable  class  of  masonry 
is  that  known  as  ashlar.  This  is  cut  stone,  accurately  dressed 
and  laid  either  in  broken  or  unbroken  ranges.  Unless  the  dress- 


K  RAILWAY     MASUXUY. 

ing  on  such  work  be  very  precise  its  superiority  ceases  to  exist. 
Especially  must  the  bed  be  cut  level  and  true,  so  that  each  part  of 
its  surface  bears  an  equal  proportion  of  the  entire  burden ;  no 
hollows,  no  scantiness,  no  bumps  can  be  allowed.  The  aid  of 
spalls  should  never  be  needed  to  get  any  cut  stone  in  proper  posi- 
tion. If  it  were  otherwise  what  use  would  there  be  of  expend- 
ing time  and  money  in  cutting  such  stone?  Generally  such 
cutting  is  done  well  and  accurately,  and  in  works  of  considerable 
magnitude  ashlar  wort  is  most  frequently  made  use  of. 


RAILWAY     MASONRY.  15 


CHAPTER  III. 

•  VARIOUS  STYLES  OF  DRESSING.  —  POINTING  JOINTS. 

In  order  to  please  the  eye  various  styles  of  dressing  the  faces 
of  stone  work  have  been  adopted,  and  that  to  be  chosen  de- 
pends upon  the  taste  of  the  builder.  Such  dressing  is  merely 
for  external  effect  and  bears  no  relation  whatever  to  the  strength 
and  durability  of  the  work,  for  as  before  remarked,  the  only 
points  essential  are  the  dressing  of  the  stone  to  true  and  level 
beds  and  reasonable  side  joints.  Unlike  most  other  work  the 
masonry  of  railway  bridges  is  very  little  seen  by  the  general 
public,  to  whose  eye  the  builders  of  other  work  almost  invariably 
cater.  Therefore  money  expended  in  costly  styles  of  stone 
cutting  on  rail  *  ay  bridge  work  serves  no  practical  purpose  and 
gratifies  the  eye  of  no  one  but  the  builder  and  the  track  walker. 
For  these  reasons  the  style  of  dressing  generally  chosen  for  the 
faces  of  abutments  and  piers  is  the  ordinary  face  of  the  stone  as 
it  leaves  the  quarry,  be  that  face  plain  and  straight,  indented  or 
protruding.  This  is  called  quarry  or  rock  faced.  If  some  of  the 
stones  have  a  rather  dull,  smooth  face,  and  are  to  be  set  in  a 
course  with  others  the  faces  of  which  are  bold  and  projecting,  it 
is  in  good  taste  to  pitch  the  edges  of  the  smooth  faced  ones  off,  so 
as  to  cause  the  centre  of  the  face  to  project  to  some  extent  beyond 
the  edges,  by  which  the  setting  of  the  course  in  a  straight  line  is 
guided.  This  pitching  off  produces  a  more  uniform  effect,  and 
its  cost  is  so  trifling  that  it  would  require  considerable  effort  to 
restrain  most  builders  from  adopting  pitch  faced  work. 

In  this  class  of  work  a  draft  or  margin  more  or  less  elaborate 


16  RAILWAY     MASONRY. 

and  distinct  must  be  tooled  around  the  four  edges  of  the  face,  in 
order  to  set  the  work  in  line  and  with  the  proper  batter.  These 
guides  may  be  pitched  off  quite  rapidly  with  the  ordinary  pitch- 
ing tool  or  wide  chisel.  There  is  no  necessity  whatever  for  work- 
ing an  accurate  margin  of  precise  width  and  exact  tool  marks. 
All  that  is  called  for  is  a  sharp,  well  defined  edge,  by  which  to 
gauge  the  setting  of  each  stone  properly  in  its  course.  This 
style  of  work,  as  illustrated  in  the  cut  of  pitch  faced  pshlar,  is 
rough,  jagged  and  massive,  and  in  appearance  is  infinitely  more 
grand  and  imposing  than  smooth  faced  work. 

A  very  beautiful  though  costly  style  of  work,  rarely  used 
except  for  the  corner  blocks  and  tail  bonds  of  the  angles  of  piers 
and  abutments,  and  then  only  in  such  places  as  to  be 
seen  and  appreciated,  is  known  as  the  vermiculated,  in  which  a 
comparatively  smooth  faced  stone  is  traversed  in  all  directions 
by  a  serpentine  net  work  of  deep,  sh?rp  tool  courses,  leaving  in 
the  spaces  between,  warty  protuberances  of  some  size,  which 
stand  out  in  bold  relief  to  the  tool  courses.  This  style  of  work 
requires  an  accurately  tooled  margin  of  equal  width  and  depth 
drawn  around  all  four  of  the  face  edges,  in  order  to  set  it  off 
properly  and  as  though  enclosed  in  a  panel. 

A  cheaper  style  of  work,  which  presents  a  rather  elegant  effect, 
is  designated  the  bush  hammer  dressing.  It  is  used  only  upon 
the  softer  limestones  and  sandstones,  and  is  produced  by  a  ham- 
mer into  the  face  of  which  has  been  cut  several  deep  channels, 
crossing  each  other  at  right  angles.  This  leaves  the  vacant 
spaces  prominent :  sharp  edged  teeth  of  pyramidal  shape.  The 
striking  of  the  hammer  on  the  face  of  the  stone,  pits  the  stone 
with  numberless  little  indentations,  which  act  as  a  relief  to  the 
otherwise  smooth  face.  This  style,  too,  must  be  provided  with  a 
chiseled  margin  of  exact  uniformity.  In  bridge  masonry  it  is 


RAILWAY    MASONRY.  17 

never  used,  except  for  the  top  or  covering  course,  known  as  the 
coping.  Its  use  on  some  stone  is  objectionable,  as  .it  seems  to 
loosen  it,  and  in  course  of  time  it  is  apt  to  scale  off. 

The  only  other  style  of  dressing  for  railroad  work  of  this  char- 
acter is  known  as  the  rubbed  face.  This  is  a  smooth,  plain  face, 
produced  by  either  sawing,  ch'seling  or  rubbing  one  stone 
upon  the  other,  as  can  be  seen  exemplified  at  any  marble  works. 
Much  stone  occurs  naturally  in  quarries,  with  a  similar  face  to 
.that  produced  by  rubbing,  and  the  dry  seams  and  straight  grain 
combine  to  make  it  work  out  very  easily  and  with  straight  edges 
and  plain  face. .  But  such  a  face  is  very  monotonous  in  its 
aspect, — fully  as  much  so  as  brick.  If.  can,  however,  be  relieved 
by  working  a  moulding,  champer  or  margin  around  the  edges, 
and  beveling  the  horizontal  joints. 

A  favorite  wayof  mine  in  working  the  blue  flag  or  the  limestone, 
which  is  always  quarried  with  smooth  faces,  is  simply  to  relieve 
the  body  of  the  work  with  sandstone  corner  blocks  and  tail  bonds, 
pitch-faced  and  with  drafted  joints.  It  imparts  to  the  work 
an  air  of  solidity  and  massiveness  which  otherwise  would  be  lack- 
ing, and  the  cost  of  which  is  trifling. 

No  matter  what  the  style  of  the  cutting  or  of  the  building,  the 
appearance  of  the  work  can  be  greatly  enhanced  by  neat  and 
tasteful  pointing  of  the  joints.  The  mere  flushing  of  the  outside 
joints  is  all  that  is  absolutely  needed  as  an  adjunct  to  the  stabil- 
ity of  the  work,  but  if  cut  stone  has  been  used  to  produce  an 
effect,  the  additional  expense  of  pointing  up  should  be  incurred. 
For  this  purpose  a  mortar  of  one  part  cement,  one  part  lime,  and 
two  parts  very  fine  sand  is  used.  Flush  the  joints  full  without 
smearing  the  faces,  then  draw  straight  grocved  courses  through 
these  mortar  joints  with  the  point  of  a  steel  setting  bar  or  a  too 
made  expressly  for  the  purpose.  Or  if  the  face  of  the  work  be 


18  RAILWAY    MASONRY. 

smooth,  point  the  joints  with  the  trowel,  in  the  style  known  as 
Scotch  point,  which  resembles  the  puttied  bead  on  the  mullion  of 
an  ordinary  window  sash.  On  rubble  work  simply  strike  the 
joints  by  drawing  the  side  of  the  trowel  along  them,  holding  it  in 
an  inclined  position  so  as  to  cut  a  rather  wide  V-shaped  gash 
of  eyen  depth  and  width.  But  the  quickest  way  to  point  masonrv 
of  any  description,  is  to  smooth  the  mortar  joint  with  the  trowel 
point,  which  makes  an  even  wide  band,  and  then  draw  through 
it  a  straight,  sharp  scratch  with  the  edge  of  the  trowel,  or,  if  pre- 
ferred, draw  two  parallel  scratches.  The  neat  pointing  of  any 
kind  of  stone  work  requires  considerable  time  and  the  exercise 
of  some  little  skill,  and  unless  the  work  be  of  some  prominence  I 
make  no  pretension  to  pointing  up,  excepting  in  very  ragged  joints 
which  I  wish  to  hide,  in  which  case  pointing  mortar  becomes  of 
as  much  service  as  paint  and  putty  to  another  class  of  mechanics. 

2 


RAILWAY     MASONRY.  19 


CHAPTER  IV. 

THE  FOUNDATIONS. 

All  necessary  details  as  to  the  selection  of  the  stone  and  its 
proper  dressing  having  been  explained,  we  will  advance  a  step 
farther,  and  considering  ourselves  ready  to  begin  the  construc- 
tion of  an  open  culvert  of  some  importance,  will  devote  ourselves 
immediately  to  the  consideration  of  the  foundation,  bed,  bottom 
or  basis  upon  which  we  can  safely  build  our  masonry  with  expec- 
tation of  a  very  small  amount  of  settlement,  and  that,  in  a  uni- 
form manner,  without  rupturing  or  breaking  the  bond  of  the  ma- 
sonry. 

It  is  essential,  therefore,  that  we  begin  our  work  upon  a  firm 
and  stable  bottom,  one  which  is  practically  incompressible,  as  in 
the  case  of  bed  rock,  or  one  which  is  nearly  so,  as  in  the  case 
of  firm  level  beds  of  clay,  or  hard,  concreted  and  indurated 
gravel. 

Every  one  of  my  readers  has  seen  great  banks  of  clay,  solid, 
firm,  of  great  cohesion  and  density,  which  have  served  as  the  walls 
or  con  fines  of  some  stream  for  years.  All  this  time  the  current  is 
gradually  but  surely  cutting  out  a  deep  groove  or  shelf  under 
the  bank.  No  crumbling  or  falling  away  of  small  masses  is  re- 
marked, but  at  some  hour  the  last  hair's  breadth  in  the  groove  has 
been  cut  (like  the  last  bite  of  the  w  rm  which  fells  the  mighty 
oak)  and  the  entire  bank,  in  one  mass  of  many  tons  weight  top- 
ples over  into  the  stream  and  lies  like  a  great  boulder,  without 
fissure  or  parting,  until  completely  dissolved.  Such  a  bed  of  clay 
ie  a  most  admirable  foundation  for  piers  and  abutments,  if  of 


20  RAILWAY    MASONRY. 

» 

any  great  extent  and  depth ;  it  is  so  impervious  to  water  as  to 
remain  solid  and  never  acquire  to  any  great  extent  that  pasty, 
semi-fluid  consistency  obtained  by  ordinary  soils  and  earths. 

Every  one  has  also  noticed  great  banks  of  dark,  dingy,  brown 
gravel,  coarse  grained,. full  of  iron  and  concreted  firmly  together 
with  a  natural,  earthy  cement.  This  withstands  the  corroding 
influence  of  a  rapid  current  even  better  than  the  firm,  strong 
clay  just  mentioned.  I  have  seen  such  river  banks  that  seemed  to 
undergo  no  appreciable  change ;  no  marked  dissolution  or  caving 
was  ever  noticed ;  they  were  the  nearest  approach  in  stability,  to 
solid  masonry,  that  I  ever  witnessed.  Solid  beds  of  this,  or  even 
of  good  thick  heavy  crust  overlaying  a  treacherous  substratum, 
are  excellent  foundations  for  bridge  work. 

Beds  of  loose,  disintegrated  gravel  and  of  sand  are  also  nearly 
incompressible  so  long  as  confined  and  prevented  from  escap-, 
ing.  But  as  each  particle  is  separate  and  distinct  from  the 
other,  utterly  without  bond  or  cohesion,  it  is  powerless  to  resist 
the  action  of  running  water,  and  any  work  built  upon  such  a 
bottom  would  be  undermined  by  a  rapid  current  unless  far  from 
its  reach.  In  addition  to  thi-^,  much  sand  is  of  a  quick  or  mercu 
rial  nature ;  the  mere  seeping  of  water  into  and  through  it  ren- 
ders it  of  a  semi-fluid  character — soft,  yielding  and  treacherous, 
and  consequently  such  foundations  are  undesirable  upon  which 
to  erect  bridge  masonry.  In  fact,  no  matter  how  firm  the  ground 
and  river  bed  upon  which  a  pier  is  to  rest,  it  must  be  well  pro- 
tected against  anj  reasonable  chance  of  scour.  The  depth  of 
the  stratum  must  be  considerable,  so  that  the  work  can  be  set 
well  down  into  it,  otherwise  artificial  means  must  be  resorted  to, 
which  are  generally  an  apron  or  toe  of  heavy  rubble  or  rip-rap 
stone  cast  around  the  pier,  so  that  each  stone  finds  its  own  bed. 
In  some  instances  such  a  procedure  would  obstruct  the  channel; 


RAILWAY    MASONK?.  21 

if  so  the  mode  of  founding  must  be  one  yet  to  be  described. 
Bed  rock  is  the  only  substance  secure  against  scour  aud  abso- 
lutely incompressible,  and  to  novices  would  seem  invariably  the 
most  desirable  foundation,  but  in  actual  practice  it  is  often 
exactly  the  reverse,  It  may  present  an  extremely  broken  and 
irregular  surface,  often  smooth  and  water  worn  whether  level  or 
rounded ;  in  other  spots  broken  into  jagged  steps  and  ledges, 
with  numerous  cracks  and  fissures,  with  a  free  course  for  water 
through  them,  which  renders  the  labor  of  leveling  the  bed  quite 
considerable,  the  presence  of  water  also  making  it  exceedingly 
difficult  to  keep  it  dry  while  such  leveling  is  being  done. 

But  if  the  natural  bottom  be  really  rock,  not  a  mere  shale  or 
imperfect  formation,  no  compression  or  settling  need  be  ex- 
pected except  that  from  the  shrinkage  of  the  mortar  joints  in  the 
courses  of  the  masonry.  Our  only  necessity  therefore  is  to 
level  the  foundation  pit  so  that  the  masonry  can  start  from 
a  level  bed.  This  must  be  done  by  blasting  and  working  off  the 
irregularities  on  the  surface  of  the  rock,  or  by  filling  up  the 
fissures  and  vacuities  with  a  reliable  and  trustworthy  con- 
crete, or  if  perfectly  secure  from  scour,  as  in  the  case  of  a 
fissure,  fine  well  broken  stone  or  gravel  well  rammed,  will 
suffice.  If,  however,  the  expense  be  too  great  to  start  the  work 
from  one  level,  the  excavation  may  be  made  with  a  horizontal 
step  or  steps,  taking  care  to  execute  that  part  of  the  work  which 
contain^  the  greatest  number  of  horizontal  mortar  joints  with  a 
harder  setling  mortar  than  those  parts  where  the  work  is  not 
so  high ;  otherwise  great  difficulty  will  be  experienced  in  keeping 
the  courses  of  the  stonework  level,  the  sett'ement  being  greater 
according  to  the  increased  numbe'r  or  thickness  of  the  horizon- 
tal mortar  joints. 

Generally,  at  a  reasonable  depth,  such  natural  bottoms  are 


22  RAILWAY    MASONRY. 

found  as  I  have  just  described.  If  not,  then  an  artificial  bed 
must  be  constructed. 

It  will  therefore  be  seen  that  foundations  are  either  natural  or 
artificial. 

To  determine  upon  what  manner  of  foundation  our  culvert 
shall  be  built,  it  becomes  necessary  for  us,  in  the  first  place,  to  re- 
sort to  a  preliminary  digging,  or  if  at  considerable  depth,  boring 
in  order  to  test  the  bottom.  In  boring  I  generally  use  an  ordi- 
nary two  inch  wood  auger  with  jointed  rods  for  lengthening  it  as 
the  boring  proceeds.  This  I  work  with  three  feet  levers,  and  in 
ordinary  soils  two  men  will  make  a  boring  of  twenty  or  thirty 
feet  in  one  day. 

But  this  mode  sometimes  deceives  us  in  consequence  of  strik- 
ing upon  a  pocket  of  clay  or  gravel,  or  upon  a  chance  boulder, 
which  as  future  progress  is  made  in  the  regular  excavation  dis- 
closes its  true  character  and  makes  a  change  of  plans  unavoida- 
ble, as  well  as  an  increase  of  cost. 

As  a  rule,  however,  we  are  safe  in  forming  our  conclusions 
from  the  indications  brought  up  by  the  auger.  If  a  natural 
foundation  is  found  at  reasonable  depth  we  can  estimate  the  cost 


ARTIFICIAL  FOUNDATION — LOGS   FILLED  IN   WITU    CEMENT    AND 
PLANKED   OVER. 

of  the  work.  If  an  artificial  foundation  is  advisable  we  can  decide 
as  to  its  kind.  In  building  culverts  in  which  the  height  and 
weight  of  the  masonry  are  not  great,  I  examine  into  the  nature 
of  the  soil  of  the  banks  and  bed  of  the  stream,  and  also  ascer- 


RAILWAY    MASONRY.  23 

tain  the  depth  of  the  bed  of  the  water  course.  Unless  my  abut- 
ment is  to  set  well  back  into  the  bank,  perfectly  safe^from  scour 
and  undermining,  or  is  to  be  protected  by  a  rip-rap  toe,  I  invar- 
iably set  the  foundation  several  feet  below  the  bed  of  the  stream, 
varying  as  I  find  the  tendency  of  the  channel  has  been  to  deepen 
or  widen  from  tne  scouring  of  the  current. 

At  what  I  think  to  be  a  sufficient  depth  for  the  starting  of  my 
footing  course,  secure  from  undermining,  I  cease  the  work  of  ex- 
cavating. If  the  bottom  of  the  trench  be  a  hard  crust  of  clay  or 
gravel,  overlaying  soft  earth,  or  if  it  is  an  ordinary  loamy  soil, 
not  very  firm,  or  peaty  and  full  pf  vegetable  fibre  as  in  marshes 
or  in  any  soil  which  is  somewhat  soft  and  compressible,  and  not 
firm  enough  to  bear  the  weight  of  the  masonry  and  its  load  with- 
out some  equal  distribution  of  the  pressure  over  considerable 
surface,  I  level  the  bottom,  and  then  lay  down  timbers  or  sleep- 
ers transversely  with  the  excavation,  generally  using  oak  ties. 
These  I  place  eighteen  inches  apart,  filling  the  vacant  places 
flush  with  very  strong  concrete,  made  of  fine  broken  stone,  mixed 
with  equal  parts  of  sand  and  cement.  Upon  this  bed,  longitudi- 
nally with  the  excavation,  is  laid  and .  spiked  a  two-inch  plank 
floor,  sometimes  adding  another  thickness,  which  is  laid  so  as  to 
cross  the  joints  of  the  lower  course  diagonally,  also  spiking  this 
layer.  This  mode  makes  a  very  strong  bed  upon  which  to  start 
the  masonry,  and  any  settlement  upon  a  spongy  and  compressi- 
ble soil  will  be  uniform.  I  have  rarely  found  it  necessary  to 
draw  back  the  footing  course  of  stone  more  than  six  inches  from 
the  edge  of  the  plank  flooring,  although  the  greater  the  extent 
of  flooring  the  less  is  the  liability  of  settling. 

Jf  the  timber  is  good  and  the  ground  wet,  which  latter  is 
always  the  case,  no  fears  of  decay  need  be  entertained.  Under 
ordinary  circumstances,  for  abutments  of  culverts  this  is  not 


24  RAILWAY     MASONRY. 

only  the  most  inexpensive  artificial  foundation  but  is  also  a  re- 
liable one. 

The  other  artificial  foundations  will  receive  due  attention  in 
future  chapters,  the  next  in  course  being  piling  and  the  circum- 
stances under  which  it  is  advisable. 

It  often  occurs,  however,  that  the  ground  is  too  spongy  and 
compressible  to  render  the  artificial  foundation  just  described, 
advisable.  The  depth  of  the  soil  above  the  hard  stratum  may 
be  so  great  as  to  make  the  bringing  up  of  the  tolid  masonry 
from  it  an  expensive  matter,  in  which  case  I  proceed  as  follows: 

I  make  the  excavation  a  reasonable  depth  below  low  water 
line,  say  four  feet.  I  then  pile  the  pit,  setting  the  piles  from 
two  and  one  quarter  to  five  feet  apart,  from  center  to  center, 
according  to  the  weight  of  the  masonry  to  be  put  upon  them.  The 
heads  of  the  piles  are  cut  off  level  some  three  or  four  inches 
beneath  low  water  line ;  they  are  then  all  connected  together  by 
wales  or  wooden  strips,  set  into  shoulders  or  daps,  and  spiked. 

This  then  leaves  a  vacant  space  between  each  four  piles  some 
three  feet  and  over  in  depth.  This  I  fill  flush  up  to  the  top  of  the 
heads  with  concrete  of  four  or  five  parts  finely  broken  stone 
mixed  up  with  a  mortar  of  one  part  cement  and  two  parts  sand. 
I  never  use  a  poor  concrete.  My  object  is  not  to  see  how  much 
sand  I  can  use  or  how  little  cement  or  lime ;  my  purpose  is  to 
form  an  artificial  stone  which  adjusts  itself  to  all  the  knotiy  ex- 
crescences and  unequal  shapes  of  the  piles,  moulds  itself  around 
them  tightly  and  closely  and  in  course  of  time,  if  well  rammed 
down,  hardens  into  stone  as  strong  and  durable  as  limestone;  the 
piles  then  really  being  imbedded  into  one  solid  mass  of  rock, 
where  if  movement  or  settling  takes  place,  all  must  be  together 
and  uniform. 

This  is,  if  properly  made,  an  admirable  artificial  foundation. 


RAILWAY    MASONRY. 


25 


Culvert  work  never  requires  any  better.     The  illustration  shows 
this  method  as  adapted  to  an  under  water  foundation  for  pier. 


PILING  FOUNDATION  FILLED  IN  WITH  CONCRETE. 

Upon  the  surface  of  the  foundation  just  described  I  step 
with  satisfaction  and  start  the  footing  course  of  my  masonry. 

Before  commencing  my  excavation  I  give  some  thought  to  its 
size  and  shape.  These  depend  upon,  first,  the  amount  of  protec- 
tion, if  any,  needed  for  the  sides  of  the  embankment.  Second, 
thickness  of  wall  requisite  to  withstand  the  outward  thrust  and 
pressure  of  the  embankment  head. 

If  the  embankment  is  high  the  sides  will  need  to  be  retained 
by  a  wing  from  the  abutment  proper.  A  five  foot  wing  extend- 
ing at  an  angle  of  forty -five  degrees  from  the  main  wall  is  my 
favorite,  but  the  stone  requires  considerable  hammer  work  to 
shape  it  for  the  splayed  corners  necessary — whereas  stone  for  rect- 
angular corners  is  much  more  easily  put  in  shape,  for  which  rea- 


36  RAILWAY     MASONRY. 

son  I  generally  build  rectangular  wings.  If  the  stream  washes 
at  the  foot  of  the  embankment  I  lengthen  the  wing  at  that  place 
accordingly.  The  higher  the  embankment  the  greater  the  out- 
ward pressure.  I  usually  undertake  to  secure  a  width  of  two 
and  one-half  feet  at  the  finish  of  my  work,  upon  which  the  wall 
plate  is  laid.  In  heavy  bridge  work  this  same  finish  at  coping 
should  be  five  to  eight  feet,  but  this  is  sufficient  for  cul- 
verts. 

As  I  do  not  wish  to  have  the  base  of  my  abutment  more  than 
four  or  five  feet  wide,  I  vary  the  batter  according  to  its  height, 
setting  back  my  work  as  much  as  one  to  six  for  low  wall,  which 
is  two  inches  to  one  foot  in  rise.  I  am  now  working  an  abut- 
ment twenty  feet  in  height,  in  which  I  batter  my  work  one  tc 
twenty-four,  or  only  one  inch  in  two  feet  rise.  I  rarely  build 
any  work  entirely  plumb,  because  such  width  of  wall  is  not 
needed  at  the  finish,  but  more  especially  because  a  battered  wall 
preserves  itself  better  against  the  pressure  of  the  embankment 
and  is  not  nearly  so  easily  thrust  out  of  plumb,  thereby  ren- 
dering the  falling  of  the  work  imminent  and  disastrous  to  life 
as  well  as  property. 

All  this  decided,  I  am  ready  to  lay  out  my  pit.  Unless  an 
oblique  work  is  called  for  I  lay  out  the  face  of  my  abutment 
proper  at  right  angles  with  the  track.  I  have  had  this  done  very 
accurately  and  to  the  exact  hair's  breadth,  and  amply  verified  by 
the  engineers  provided  by  the  company,  but  as  it  generally  con- 
sumes two  day's  time  before  these  gentlemen  are  sufficiently  oat- 
isfied  that  all  stakes  are  correct  and  the  crosses  on  the  stake 
heads  in  exact  position,  I  weary  of  the  delay  and  now  lay  one 
off  in  less  than  half  an  hour,  which,  although  perhaps  not  so 
exact  as  if  done  with  the  aid  of  instruments,  is  certainly  expedi- 
tious and  sufficiently  accurate  for  all  practical  purposes. 


RAILWAY     MASONRY.  2? 

The  following  cut  shows  a  method  of  protecting  piling  with 
a  wrought  or  cast  iron  shoe,  for  driving  in  hard  strata. 


PILING  WITH  IRON  SHOE. 

On  the  road  bed  about  eight  feet  back  from  the  face  of  my 
proposed  abutment,  I  establish  my  center.  I  drive  a  nail  in  the 
tie  and  with  one  end  of '  a  ten  foot  pole  pressed  against  the  nail  I 
rest  the  other  end  upon  one,  of  the  rails  and  chalk  the  spot.  I 
then  sweep  the  pole  across  to  the  other  rail  and  chalk  it.  I  have 
simply  described  the  arc  of  a  circle,  and  a  line  drawn  from  the 
chalk  mark  on  one  rail  to  the  same  on  the  other  will  be  at  right 
angles  to  the  direction  of  the  roadway,  and  so  if  the  line  is  car- 
ried on,  which  I  do  by  a  pole  from  which  I  drop  down  my  plumb 
bob,  and  drive  the  stake.  This  is  done  on  the  other  side,  and  a 
line  drawn  from  stake  to  stake  is  rectangular  with  the  stringers 
above.  If  the  track  is  oblique  I  draw  lines  from  the  outside  of 
one  rail  at  one  end  of  the  opening  and  extend  it  to  the  outside  of 
the  rail  at  the  other  end.  On  the  other  side  I  draw  another  line, 
only  using  the  inside  of  the  rails  instead  of  the  outside.  Now, 


28  RAILWAY     MASONRY. 

instead  of  resting;  one  end  of  my  pole  upon  the  actual  rail?, 
I  mark  these  strings  and  obtain  thereby  a  line  oblique  with  the 
track  and  in  exact  degree  required.  There  are  other  ways  of 
accomplishing  the  same  end,  but  this  suits  my  purpose  best. 

When  all  is  ready  to  commence  my  footing  course,  I  have 
mortar  made,  composed  of  one  part  cement  to  two  of  good  sharp 
sand.  I  use  this  cement  mortar  until  far  above  the  ordinary 
water  level,  when  I  use  lime  one  part,  ashes  one  part,  and  sand 
three  to  five  parts,  just  as  I  find  the  sand  requires,  for  some  sands 
are  naturally  hungry  and  require  a  large  proportion  of  lime.  No 
just  rule  can  be  laid  down,  only  this :  never  let  it  get  above  five 
parts  sand  to  one  of  lime.  The  ashes  I  use  because  they  make 
the  lime  mortar  set  like  a  cement  mortar  and  impart  some  con- 
siderable degree  of  hydraulic  energy  to  it  and  render  it  imper- 
vious to  the  moisture,  which  would  otherwise  decompose  the 
ordinary  lime  mortar.  Either  coal  or  wood  ashes  are  good,  and 
in  their  absence  brick  dust  will  be  found  no  mean  auxiliary  to 
the  lime. 

When  the  work  is  completed  I  point  up  the  joints  with  a  mor- 
tar of  one  part  cement  and  one  part  sand,  into  which  is  worked 
one  part  lime  to  make  the  mortar  work  easily  and  adhere  where 
thrown. 


RAILWAY     MASONRY. 


CHAPTER   V. 

MANNER    OF    CONSTRUCTION — ABUTMENTS. 

Having  taken  into  consideration  the  height  of  embankment  and 
pressure  exerted  outwardly  upon  any  masonry  erected  to  with- 
stand this  outward  thrust,  and  having  decided  upon  the  shape 
and  thickness  of  abutment,  which  thickness  is  also  regulated  to 
a  great  extent  by  the  width  of  the  foundations  upon  which  we 
are  to  build,  we  turn  our  attention  to  the  masonry.  If  the  work 
is  one  of  no  great  importance, — if  the  height  of  the  opening,  and 
consequently  the  weight  of  the  masonry  itself  are  slight,  I  care 
for  nothing  better  than  good  solid  rubble  laid  in  ranges,  roughly 
hammer-dressing  the  side  joints  into  perpendicular  and  pointing 
or  picking  off  any  glaring  inequalities  on  the  beds ;  being  careful 
to  lay  each  stone  so  that  it  overlaps  the  joints  of  the  work  in  the 
lower  course,  and  at  the  same  time  spalling  up  any  requiring  it 
so  as  to  put  it  upon  a  level  with  the  others  of  the  same  course. 
Where  the  stones  do  not  fit  closely  I  fill  the  vacuities  with  broken 
stone  and  mortar,  which  in  time  become  equally  hard  with  the  stone. 


SECTION  OF  WING  AND  ABUTMENT. 

The  general  construction  of  this  work  is  shown  in  the  illustration 
of  footing  courses  of  an  abutment  with  diagonal  wings,   the 


30  RAILWAY    MASONRY. 

dotted  lines  showing  about  how  the  joints  of   the  upper  course 
break  those  of  the  lower. 

If  the  work  is  of  still  less  importance,  and  the  height  of  open- 
ing perhaps  but  four  or  five  feet,  consequently  needing  much 
less  strength,  I  should  face  my  work  with  layer  stone  laid  in 
courses,  with  occasional  headers  laid  through  or  at  least  nearly 
through  the  wall,  so  as  to  bind  it  thoroughly.  The  back  I 
should  build  of  the  ordinary  rubble  or  waste  rock  of  my  quarry, 
and  fill  in  between  with  the  same  or  with  a  first  class  concrete  of 
broken  stone.  If  good  rich  mortar  is  used  in  such  work,  the  in- 


ABUTMENT  IN-  RUBBLE  RANGE  WORK — END  ELEVATION. 

tericr  of  the  mass  will  in  course  of  time  become  much  more  solid 
and  harder  than  any  sandstone.  No  trouble  need  ever  be  expe- 
rienced from  it,— I  have  used  it  as  the  filling  of  very  heavy  bridge 
abutments  and  piers,  the  outside  being  faced  with  cut  stone  and 
the  headers  running  back  and  through,  resting  upon  the  concrete. 
Then  by  the  addition  of  more  concrete  the  header  becomes  com- 
pletely imbedded  in  it  and  so  thoroughly  cemented  as  to  fracture 
through  the  stone  before  parting  from  its  concrete  bed.  For  the 
lower  work  cement  concrete  is  needed;  above  that  the  lime  con- 
crete will  answer.  In  making  concretes  I  simply  make  up  a  bed 
of  mortar  into  which  I  shovel  damp  broken  stone  until  the  mor- 


RAILWAY    MASONRY. 


31 


tar  can  take  up  no  more.  I  hoe  this  mass  over  thoroughly  so 
that  each  and  every  stone  becomes  well  coated  with  mortar,  and 
carry  it  into  the  work.  This  mass  eventually  becomes  a  conglo- 
merate stone  of  great  hardness,  and  where  good  stone  is  expen 
sive  can  be  employed  to  advantage,  but  usually  it  is  more  costly 
than  solid  stone  work. 

As  before  remarked,  in  some  situations  concrete  is  cheaper 
than  well  shaped  stone,  while  in  others  it  is  costlier. 

1  vary  my  modes  of  construction  for  the  very  good  reason  that 
I  wish  my  quarry  kept  clean  and  free  from  the  waste  stone  and 


'ABUTMENT  IN  RUBBLE  RANGE  WORK — VERTICAL  SECTION. 

dirt  that  are  always  accumulating.  The  earth  which  is  uncovered 
from  the  stone  I  load  upon  the  cars  and  set  out  upon  some  side- 
track until  I  have  need  of  it — and  I  have  invariably  found  occa- 
sions for  the  use  of  earth  for  filling  around  my  work  in  finishing 
up — in  which  case  the  loaded  cars  come  in  very  acceptably. 

Again,  between  the  layers  of  the  rock  are  ledges  of  shale  and 
shingle,  which  pick  and  blast  out  in  very  small  fragments,  and 
require  so  little  exertion  to  break  up  into  a  size  that  will  pass 
through  a  two  or  three  inch  ring,  that  I  have  had  one  man  re- 


82  RAILWAY     MASONRY. 

duce  an  entire  car  load  in  one  day.  This  as  well  as  the  junk 
stone  I  set  out  and  use,  because  under  such  circumstances  I  can 
do  it  profitably  and  at  the  same  time  keep  my  quarry  in  working 
shape.  It  is  not  from  preference  that  I  do  so,  however,  as  the 
company  has  an  excellent  crusher  located  on  the  road  from  which 
I  have  never  asked  or  received  a  single  car  of  broken  stone.  That 
I  prefer  large  stone  is  evident  from  the  fact  that  I  use  the  rub- 
ble and  concrete  only  in  the  minor  works. 

i  Both  classes  of  this  work  are  shown  on  pages  30  and  31 .  All  that 
is  necessary  to  render  them  worthy  of  consideration  is  conscien- 
tious workmanship  executed  with  tlrst-ciass  mortar.  From  mo- 
tives of  economy  their  adoption  is  rarely  advisable  unless  under 
circumstances  similar  to  those  noted,  and  even  then  the  constant 
supervision  of  the  foreman  is  required  to  see  that  the  work  is 
well  executed. 

Upon  most  American  roads  masonry  is  a  secondary  matter  and 
is  generally  built  after  the  road  has  been  opened.  When  first 
constructed  piling  and  timber  are  freely  used,  but  the  road  being 
put  in  operation  then  comes  the  substitution  of  masonry  under 
all  manner  of  drawbacks  and  obstacles.  The  stone  must  either 
be  unloaded  along  the  track  at  some  distance  from  the  work, 
upon  a  level  grade,  or  put  upon  the  side  of  some  steep  em- 
bankment at  the  work  and  also  scattered  in  the  dry  bed  of 
the  stream.  The  dirt  from  the  excavation  becomes  quite  a  hin- 
drance, and  the  piles,  bents  or  struts  interfere  greatly  with  the 
free  working  of  the  derrick. 

The  sand  pile,  mortar  beds,  water  barrels,  material,  etc.,  all 
combine  to  make  everything  crowded  and  inconvenient.  Sand, 
perhaps,  must  be  brought  from  a  distance ;  even  the  stream  may 
be  dry  and  water  must  be  pushed  on  a  car  from  some  other  stream 
or  taken  from  the  tank  of  some  passing  locomotive.  Considera- 


RAILWAY    MASONRY.  3S 

ble  allowance  must  therefore  be  made  for  such  loss  of  time.  Be- 
fore beginning  the  excavation  the  track  must  be  well  protected 
from  any  danger  which  would  ensue  from  the  caving  in  of  the 
embankment,  which  always  happens  more  or  less.  This  protec- 
tion is  afforded  by  putting  in  additional  lengths  of  stringers  which 
reach  well  back  upon  the  embankment  and  which  can  be  upheld 
near  the  excavation  by  bents  or  a  crib  of  ties,  so  that  the  work 
can  go  steadily  on  without  holding  trains  or  delaying  the  work 
until  they  have  passed  over. 

The  mere  building  of  the  stone  work  generally  occupies  much 
less  time  than  making  ready  for  it  and  finishing  up  afterwards, 
and  it  is  essential  that  such  masonry  should  be  built  so  as 
to  be  permanent,  that  all  the  confusion  and  expense  may  require 
no  repetition.  The  entire  matter  is  one  needing  the  exercise  of 
considerable  judgment.  There  are  cases  where  an  excellent  ma- 
terial foundation  can  be  found  at  very  slight  depth,  where  there 
is  no  danger  whatever  from  scour,  and  where  the  excavation  of 
deep  trenches  would  be  a  waste  of  money.  There  are  others 
where  the  embankments  need  walling  up  with  heavy  wings  or 
strong  retaining  walls.  In  some  cases  these  wings  should  extend 
in  height  almost  to  the  top  of  the  grade:  in  others  their  height 
jneed  be  inconsiderable  and  the  edge  of  the  embankment  should 
rest  upon  the  tops  of  the  wall,  such  being  then  a  surcharged 
retaining  wall. 

Again,  very  often  the  sides  of  the  embankments  require  no  aid 
whatever  in  the  form  of  stone  work,  or  perhaps  at  most  require 
tome  loose  rubble  thrown  along  their  base.  In  fact,  what  will 
answer  in  one  situation  will  not  in  another.  In  one  an  open  cul- 
vert is  preferable,  in  others  a  box  or  an  arched  culvert  is  bet- 
ter,— and  these  we  will  next  consider. 
3 


34  RAILWAY    MASONRY. 


CHAPTER  VI. 

BOX   AND  ARCH  CULVERTS. 

A  box  culvert  is  one  provided  with  a  flat  roof  or  cover  of  stone, 
reaching  from  one  wall  or  pier  to  another  parallel  wall  and  rest- 
ing thereon.  Such  opening  is  of  necessity  narrow,  and  unless 
unusually  long  and  heavy  stones  are  used  it  can  rarely  ex- 
ceed four  to  six  feet  in  width,  as  it  must  be  remembered  that 
the  covering  stone's  must  lap  over  upon  the  piers  which  sustain 
them.  The  embankment  must  also  be  of  considerable  height, 
for  it  is  absolutely  necessary  that  at  least  two  feet  of  earth  shall 
rest  upon  the  roof  between  it  and  the  ties.  This  earth  acts  as  a 
cushion  in  softening  the  shock  of  a  passing  train.  In  the 
absence  of  a  sufficient  layer  of  earth  the  roof  would  be  broken, 
not  from  the  weight  of  the  train  but  Irom  the  repeated  ham- 
mering blows  of  the  wheels. 

The  excavation  for  a  box  culvert  should  include  not  only  the 
space  to  be  occupied  by  the  walls  or  piers  but  also  all  the  inter- 
mediate space  between.  The  bottom  should  be  brought  either 
to  a  uniform  level  or  hollowed  out  in  the  centre  from  end  to 
end  and  paved  with  good  large  stone  that  will  not  be  washed 
out  by  the  current. 

The  two  sides  of  this  pavement  will  serve  as  footing  courses 
for  the  walls  of  the  culvert.  The  covering  should  be  of  rectan- 
gular stones  fitting  closely  together,  so  that  in  case  the  embank- 
ment is  high  each  stone  need  bear  only  the  weight  of  the  earth 
directly  above  it.  In  general  too  little  care  is  taken  with  this 
class  <)f  work.  The  excavation  is  made  very  slight,  the  culvert 
bottom  often  being  considerably  above  the  surface  of  the  adja- 


RAILWAY    MASONRY. 


35 


cent  land,  making  drainage  impossible  but  complaint  from  the 
land  owner  certain  and  earnest. 

The  roof  is  often  made  simply  of  several  long  stones  laid  a 
foot  or  more  apart,  like  the  rafters  of  a  timber  roof,  and  across 
from  one  stone  rafter  to  the  other  is  laid  any  rubbish  in  the  shape 
of  stone  that  will  cover  the  space.  As  a  consequence  each  long 
stone  must  support  not  only  the  weight  of  earth  directly  over  it 
but  also  that  over  the  stones  that  lap  from  it  to  its  fellow.  In 


BOX  CULVERT,  WITH   PAVEMENT. 

the  case  of  a  heavy  embankment  such  additional  weight  often 
proves  too  much  and  breaking  in  of  the  roof  takes  place,  and  in 
order  to  repair  this  damage  an  excavation  perhaps  twenty  or 
thirty  feet  or  more  in  depth  must  be  made  to  get  at  the  work 
and  rebuild  it. 

Such  work  should  I  e  well  built  ot  heavy  stone,  and  every  pre- 
caution should  be  taken  against  breaking  in  of  walls  or  roof.  I 
lately  built  a  double  culvert,  one  chamber  of  which  was  com- 
posed of  only  seven  stones  in  its  two  walls  and  nine  in  the  roof. 


86 


RAILWAY     MASONRY. 


The  extreme  size  ami  weight  of  these  stones  made  them  slow  and 
tedious  to  handle,  but  the  strength  and  permanence  of  the  work 
amply  compensated.  Diagonal  wings  are  essential  to  the  entrance 
and  also  to  the  exit,  and  the  space  between  should  be  paved,  so 
that  no  holes  can  be  worn  by  the  rush  of  the  water,  which  would 


(Ws*r/:s.-  ^^xx^xx^^-xx//////.///-/^/""™.^..  .  ^T^y..^NW w^-vxxxxxxxJS 


ARCHED  CULVERT  OF  CUT  STONE. 

form  eddies  resulting  in  the  undermining  of  the  culvert  proper 
and  perhaps  wearing  a  passage  under  the  floor  or  along  its  sides, 
preparing  the  way  for  a  washout. 

A  costlier  and  more  important  class  of  work  is  known  as  the 
arched  culvert  of  which  a  sketeh  is  shown  below.  In  this,  a  a 
ere  the  impost  stones  or  tops  of  the  piers  from  which  the  arcb 


RAILWAY    MASONRY. 


87 


springs.  The  distance  between  these  is  called  the  span  of  the 
arch.  The  height  from  the  level  of  the  imposts  up  to  the  key- 
stone b  is  called  the  rise  of  the  arch,  the  inside  curve  *is  the  sof- 
fit, while  the  outer  or  upper  curve  is  called  the  extrados  and 
each  stone  which  is  a  member  of  the  arch  is  designated  a  voussoir. 

Before  building  an  arch  a  timber  framing  or  centering  is  put 
into  position,  and  commencing  at  the  imposts  the  voussoirs  are 
laid  upon  this  framing  until  all  the  keystones  are  inserted,  which 
bind  the  work  together  so  that  the  framing  can  be  removed. 

In  this  class  of  work  accurately  dressed  stone  should  be  used, 
not  only  in  the  arch  itself  but  also  in  the  piers.  A  reliable  and 
uniform  foundation  is  the  onfy  kind  upon  which  such  work  should 


v. 

¥ 


< j^t?i/i 

l^TxJl 


ENGLISH   BOND—  EVERT  ALTERNATE  COURSE  HEADERS. 

be  started,  as  any  sinking  of  the  haunches  will  tend  to  settle  the 
lower  courses  of  the  arch  and  spring  the  voussoirs  away  from 
the  keystones,  weakening  the  arch  and  quite  likely  causing  it  to 
fall  in.  For  this  reason  dressed  stone  should  be  used  in  the 
piers.  Again,  in  the  arch  rubble  stone  could  be  used,  but  on 
account  of  the  shape  of  the  undressed  stone  much  mortar  will  be 
required.  This  of  course  fills  up  all  vacancies  and  irregularties, 
and  acts  as  the  key  or  wedge  which  holds  the  work  together. 


38 


RAILWAY     MASONRY. 


Now  let  this  mortar  decompose,  soften,  crack  and  fall  out  to  any 
appreciable  extent  and  the  work  must  fall,  because  that  which 
tightened  it  and  held  it  together  is  gone,  just  as  knocking  out  the 
wedgef  from  a  lot  of  blocking  will  loosen  it. 

The  better  plan  is  to  cut  the  voussoirs  into  exact  shape  and 
rely  upon  this  shape  to  uphold  the  arch  and  use  only  so  much 
mortar  as  is  necessary  to  cement  the  work  together.  On  account 
of  this  accurate  dressing,  brick  is  now  more  frequently  used  than 
stone  in  the  construction  of  arches,  and  where  much  of  this  class 
of  work  is  to  be  done,  instead  of  using  the  ordinary  rectangular 


HORIZONTAL   SECTION  THROUGH  WALL. 

(Showing  headers  running  through  the  wall,  and  stretchers  lengthwise 
with  the  wall.) 

brick,  beveled  ones  should  be  made,  the  arches  being  shaped  to 
suit  the  bevel  of  the  bricks — let  the  result  be  an  eliptical,  semi- 
eliptical,  gothic  or  any  other  form  of  arch. 

In  former  days  many  expensive  stone  bridges  were  constructed 
with  arches  of  almost  incredible  span.  The  railroads  of  to-day 
find  iron  bridges  resting  upon  stone  piers  preferable,  and  beyond 
culvert  work,  very  few  arched  water  ways  are  now  built  and  these 
only  where  the  height  of  the  embankment  makes  them  cheaper 
than  open  culverts.  Therefore,  little  if  any  more  need  be  said 
concerning  them. 

We  will  now  turn  to  that  class  of  work  wherein  not  only  all 
the  difficulties  of  founding  the  piers  of  culverts  are  experienced, 
but  where  the  presence  of  water  acts  as  an  additional  obstacle — 


RAILWAY     MASONRY.  39 

where  some  mode  of  protection  must  be  adopted  against  this 
troublesome  element.  The  artificial  foundations  already  illus- 
trated can  be  used  f«  r  tie  abutments  and  piers  of  heavy  bridges, 
but  when  such  work  must  be  set  in  the  bed  of  a  stream,  coffer- 
dams, caissons,  etc.,  are  needed  so  that  the  foundations  can  be 
kept  comparatively  dry  while  the  work  progresses. 

In  the  accompanying  illustrations  the  manner  of  laying  the 
stone  is  shown.  The  English  bond  is  considered  the  strongest 
although  either  style  will  be  found  sufficiently  massive  if  built  up- 
on a  proper  foundation.  We  are,  therefore,  left  very  little  to  con- 
sider but  hydraulic  foundations  in  future  articles. 


40  RAILWAY    MA.SONBT. 


CHAPTER  VII. 

HYDRAULIC   FOUNDATIONS 

In  carrying  out  the  construction  of  bridge  masonry  over  water 
courses  of  considerable  size,  in  addition  to  the  difficulty  often 
experienced  in  obtaining  good  foundations,  we  encounter  another 
great  obstacle  in  the  form  of  water.  Various  means  must  be 
adopted  to  make  this  drawback  as  inexpensive  as  possible.  Every 
river  bed  may  present  some  peculiarities  of  its  own,  or  some  com- 
bination, differing  from  all  others,  and  it  is  these  that  must  gov- 
ern us  in  the  modes  of  working.  In  one  place  we  may  use  piling 
or  sink  caissons  for  foundations;  in  other  places  we  may  bring 
up  solid  masonry  from  the  natural  bottom,  executing  the  work 
with  the  aid  of  the  diving  bell,  or  we  may  construct  a  cofferdam 
around  the  site  of  the  work,  and  the  interior  being  pumped  dry, 
we  can  carry  up  the  masonry  above  the  level  of  the  water  line, 
when  there  is  no  further  need  of  the  dam.  However,  I  will  enter 
into  no  theoretical  disquisition  upon  the  matter,  nor  will  I  at- 
tempt to  classify  the  various  modes  of  founding  and  the  circum- 
stances which  make  them  most  desirable.  I  will,  instead,  ex- 
plain my  views  much  better  by  entering  at  once  into  actual  prac- 
tice, wherein  the  features  of  the  river  bed,  banks  and  current 
are  varied. 

I  wish  to  build  the  abutnients  and  four  piers  for  a  bridge  to 
span  a  certain  wide  stream  as  shown  in  the  illustration.  The 
site  of  the  first  abutment  is  back  some  fifteen  feet  from  the  edge 
of  the  water  at  its  usual  stage,  in  a  heavy  bank  of  stiff,  shelly, 
blue  clay  which  rests  directly  upon  the  bed  rock  some  thirty  feet 
below  ordinary  water  level. 


41 

The  first  pier  is  located 
in  ten  feet  of  water,  over- 
laying 20  feet  in  depth  of 
mud  and  hard  clay,  and  is 
somewhat  apt  to  scour  in 
time  of  freshets. 

The  second  pier  is  to 
be  built  at  a  point  where 
the  bottom  is  perfectly  * 
smooth,  level  rock — with 
a  depth  of  water  of  some 
thirty  feet  —  the  current 
being  here  extremely 
swift  and  often  carrying 
considerable  quantities  of 
driftwood  and  ice. 

At  the  third  pier  the 
level  ledge  of  rock  has 
terminated  —  the  bottom 
is  extremely  rough,  with 
broken  bed  rock,  at  a 
depth  of  fifteen  feet. 

There  may  also  be  a 
fourth  pier  (not  shown  in 
the  illustration)  rising 
from  a  small  island  or 
bar  of  mud  and  silt  of 
semi  fluid  character,  ten 
feet  in  depth. 

The  remaining  abut- 
ment will  be  built  in  the 


42  RAILWAY    MASONRY. 

water's  edge  upon  hard  level  rock  only  three  feet  from  the 
surface. 

Commencing  with  the  first  abutment  I  excavate  my  pit  to 
a  depth  of  about  twelve  feet  from  the  surface  nearest  the  water, 
encountering  no  trouble  from  that  element,  except  from  the 
small  quantities  which  seep  in  through  several  slight  seams  in 
the  clay,  on  account  of  which  I  am  compelled  to  pump  out  and 
sheath  the  entire  work  on  one  side  with  planking,  behind  which 
I  ram  down  a  casing*  of  cement  which  cuts  off  almost  all  the 
water.  At  this  depth  I  decide  to  commence  the  masonry,  not 
thinking  it  necessary  to  carry  the  excavation  down  to  the  bed 
rock,  because  the  pit  is  so  far  back  from  any  danger  of  scour 
from  the  current  that  any  further  expenditure  would  be  uncalled 
for.  I  would  like  to  have  set  the  masonry  directly  upon  the  clay 
or  upon  a  light  bed  of  cement  concrete,  but  the  leakage  of  water 
into  the  work  has  so  softened  the  bottom  of  the  nit  that  I  make 
use  of  timbers  laid  transversely  with  the  trench  and  filled  in  be- 
tween with  concrete  and  planked  over,  as  has  already  been  illus- 
trated in  one  of  the  chapters  on  culvert  work.  As  each  course 
of  masonry  is  laid  I  pack  the  space  between  it  and  the  sides  of 
the  pit  with  well  puddled  clay,  which  I  see  is  well  rammed  down. 
The  masonry  is  then  carried  up  in  cement  mortar  nearly  or  quite 
to  the  finish  in  the  mode  already  explained. 

This  is  not  therefore  properly  a  hydraulic  foundation,  but  in 
the  execution  of  the  first  pier  I  find  my  work  must  be  carried 
uv  through  twenty  feet  of  stiff  clay  and  mud,  over  which  flows 
at  ordinary  stages  some  ten  feet  of  water.  At  considerable  ex- 
pense I  could  build  a  cofferdam  around  the  site  of  this  pier,  and 
either  start  the  masonry  from  the  bed  rock  or  set  it  down  in  the 
clay,  as  with  the  first  abutment,  but  I  do  not  desire  to  go  down 
to  the  bed  rock  on  account  of  the  cost;  and  again,  on  the  other 


RAILWAY    MASONRY.  43 

hand,  I  notice  some  little  evidences  of  scouring  which  create 
doubt  in  my  raind  as  to  the  permanency  of  any  work  merely  set 
down  into  the  clay,  as  it  would  evidently  stand  in  danger  of 
being  undermined  sometime.  Therefore  as  the  clay  and  mud 
are  sufficiently  dense  to  hold  up  in  the  perpendicular  any  piles 
that  I  might  drive,  I  put  in  a  pile  foundation  such  as  already 
shown  in  a  previous  chapter  on  culverts. 

Bed  rock  being  within  easy  reach  of  a  thirty  foot  pile,  instead 
of  using  short  piles,  which  would  penetrate  only  a  part  of  the 
depth  of  the  clay,  I  make  use  of  those  which  will  strike  the  rock 
and  act  in  reality  as  posts,  in  which  case,  provided  the  piles  are 
of  sufficient  strength,  no  settlement  in  the  pier  would  be  visible 
except  that  caused  by  slight  shrinkage  of  the  mortar  in  the  hori- 
zontal joints  of  the  masonry.  But  were  the  bed  rock  at  much 
greater  depth  I  would  not  drive  the  piles  with  the  intention  of 
resting  them  as  in  this  case  upon  the  solid  rock. 

Elaborate  tables  have  been  prepared  by  eminent  authorities  by 
which  we  are  supposed  to  determine  the  safe  load  a  pile  can  carry 
— ras  for  example,  "  the  force  of  the  blow  by  a  ram  of  certain 
weight  falling  a  certain  distance  being  given,  to  find  the  dead 
weight  or  pressure  which  the  pile  would  sustain,  etc."  But  in 
actual  practice  these  formulae  and  rules  often  prove  sadly  defi- 
cient in  accuracy,  for  in  the  majority  of  these  tables  the  calcula- 
tions assume  the  soil  to  be  homogeneous  or  of  the  same  nature 
from  top  to  bottom,  whereas  in  reality  there  often  occur  cases 
where  the  piles  pass  through  strata  of  alluvium,  shale,  clay,  sand, 
hard  pan,  etc.,  and  although  they  may  resist  the  hammer,  it 
is  sometimes  difficult  to  determine  how  much  of  this  resistance 
is  due  to  mere  lateral  friction,  and  how  much  to  a  hard  stratum. 

The  better  way  in  starting  such  work  is  to  drive  a  test  pile  or 
soin  order  to  determine,  if  possible,  the  required  length  for  the 


44  RAILWAY    MASONRY. 

regular  foundation.  Generally  a  pile  should  be  driven  until 
it  will  not  sink  more  than  one  inch  under  the  last  blow  of  the 
monkey.  Piles  have  been  driven  only  twenty  feet  in  stiff  clay 
and  sustained  a  weight  of  eighty  tons,  but  not  more  than  one- 
quarter  that  weight  is  often  required  to  be  upheld  by  any  pile, 
and  in  mud  and  marsh  bottoms  care  must  be  taken  to  drive 
it  sufficiently  deep  so  that  the  lateral  friction  alone  can  be  re- 
lied upon  to  offer  considerable  resistance  to  the  sinking  of  the 
pile  under  a  reasonable  amount  of  dead  weight.  Foremen  of 
the  pile  drivers,  if  experienced,  generally  know  best  about 
the  soils  and  bottoms  along  the  line  of  the  road  which  employs 
them.  They  have  generally  some  pretty  clear  ideas  about  what 
manner  of  deposit  the  pile  is  penetrating — know  when  the  pile 
has  set  and  are  quite  apt  to  be  very  positive  when  they  have  struck 
solid  rock,  and  their  judgment  can  generally  be  deferred  to  with 
a  conviction  that  they  are  not  very  far  out  of  the  way,  if  at  all. 
In  passing  through  some  strata  it  is  often  necessary  to  ring 
the  heads  of  the  piles  with  iron  bands  or  rings,  to  prevent  split- 
ting the  piles  under  the  blows  of  the  hammer,  \lso  to  shoe  the 
points  with  cast  or  wrought  iron,  sawing  off  the  extreme  point  of 
the  pile,  and  making  a  shoulder  or  socket  in  the  iron  shoe  into 
which  this  sawed  off  end  will  fit.  Such  a  shoe  will  stand  consid- 
erable heavy  driving  though  much  resistance  be  offered.  If, 
however,  the  pile  is  sharpened  down  to  a  point  and  the  iron  fits 
close  to  it  the  sharp  point  will  act  as  a  wedge  and  split  the  shoe. 
But  I  will  return  to  the  pier.  When  all  the  piles  are  driven 
they  are  cut  off  to  a  uniform  level  several  inches  below  the  low- 
water  line,  the  spices  between  perhaps  left  open  to  the  water  or 
closed  up  by  sheet  piles,  between  those  piles  forming  the  sides  of 
the  work,  and  the  interior  vacancies  filled  up  with  broken  stone, 
or  under  some  circumstances,  with  cement  concrete;  timbers  are 


RAILWAY     MASONRY.  45 

then  laid  upon  tbe  tops  of  these  piles  and  planked  over  as  a  plat- 
form on  which  to  lay  the  masonry.  The  piles  must  be  cut  off 
sufficiently  low  to  place  all  the  woodwork  permanently  under  wa- 
ter in  order  to  prevent  decay.  If  a  cement  concrete  filling  is 
used  considerable  additional  expense  must  be  incurred  in  order 
to  prevent  the  washing  out  of  the  cement  before  it  has  set  suffi- 
ciently to  withstand  the  water,  therefore,  I  rarely  use  it  in  such 
situations  but  adopt  another  method,  as  will  be  shown  in  piers  3 
and  3. 

The  second  pier  of  this  bridge  must  be  founded  upon  a  smooth 
level  bed  of  rock,  lying  at  the  depth  of  thirty  feet  below  t he- 
usual  stage  of  the  water  line.  The  surface  of  this  rock  is  water 
•worn  and  smooth  from  the  action  of  a  powerful  current  Avhich 
prevents  any  lodgment  whatever  of  sediment,  mud  or  sand.  The 
illustration  already  given  shows  the  site  of  this  pier  in  the  bot- 
tom of  a  ravine  or  wide  fissure  in  the  river  bed,  forming  its  chan- 
nel, through  which  is  carried  much  driftwood,  not  only  upon  the 
surface  but  also  partly  or  entirely  submerged.  A  large  body  of 
such  float  striking  and  pressing  against  a  pier  merely  setting 
upon  this  smooth  level  bed  rock  without  fastening  of  any  kind, 
Tvould  be  very  apt  to  slide  it  out  of  position,  and  in  our  work  we 
must  take  some  precautions  against  this  danger.  It  is  desired 
to  build  the  superstructure  with  spans  of  uniform  length,  other- 
wise the  pier  might  be  located  back  farther  in  a  less  exposed 
position. 

Piling  is  entirely  out  of  the  question  because  of  there  being 
no  soil  into  which  piles  could  be  driven.  I  find  the  current  so 
strong  that  a  man  in  diving  armor  can  do  nothing  unless 
its  force  is  diverted.  The  only  feasible  plan  is  to  con- 
struct a  caisson  or  huge  chest  either  with  or  without  bottom. 
The  natural  surface  of  the  rock  being  smooth  and  level,  the  ex- 


46 


RAILWAY    MASONRY. 


pense  of  a  timber  bottom  to  the  caisson  is  unnecessary.  In  fact 
these  bottoms  are  never  advisable  or  needful  except  in  two  situ- 
ations :  where  the  caisson  is  to  be  set  upon  piling,  or  where 
we  are  building  upon  marshy  or  peaty  ground  of  great  depth,  into 
which  we  expect  the  caisson  with  the  masonry  inside  to  sink  until 
it  compresses  the  soil  under  it  so  as  to  suspend  the  caisson  in  its 
midst,  or  allow  it  to  settle  down  uniformly  until  it  eventually 
touches  hard  pan  or  some  other  tirm  stratum,  of  which  I  shall 
fully  treat  hereafter. 


END   SECTION   OF   CAISSON. 

A  caisson  with  timber  bottom  must  rest  upon  a  uniformly 
level  surface,  for  if  it  is  deposited  upon  a  firm  stratum  of  uneven 
surface,  some  parts  of  the  bottom  timbers  will  be  unsupported 
and  experience  severe  cross  strain,  which  will  in  time  surely  lead 
to  very  serious  fractures  in  the  masonry.  Then  again,  if  placed 
upon  any  soft  soil  that  becomes  exposed  to  the  current,  the  work 
will  be  undermined  and  dangerous,  and  breaks  will  occur.  If  the 
bed  be  smooth,  level  and  hard,  we  do  not  need  the  timbered  bot- 
tom, because  we  can  by  a  little  scribing  of  the  lower  edges  of  the 
sides  and  ends  of  a  bottomless  caisson  place  it  so  well  in  positioD 


RAILWAY    MASONRY.  47 

that  with  the  aid  of  cement  concrete  we  can  make  it  almost  per- 
fectly water-tight.  Therefore  on  the  shore  we  construct  the 
sides  and  ends  of  the  caisson  in  panels  or  sections  so'as  to  be  de- 
tachable after  our  pier  shall  have  been  completed.  From  two  to 
four  inch  plank  will  suffice,  according  to  the  force  and  depth  of 
the  stream  in  which  it  is  to  be  placed.  The  cross  and  upright  tim- 
bers should  be  from  four  to  six  inches  in  thickness.  These  sides 
and  ends  can  be  erected  upon  ways  which  slope  from  the  shore 
to  some  distance  into  the  water  at  such  depth  as  will  float  the 
caisson  off  the  ways,  when  it  can  be  towed  out  to  its  loca- 
tion and  sunk  by  swinging  rails  on  to  the  sides  near  the  lower 
edges,  these  rails  being  drawn  up  again  when  the  caisson  is  no 
longer  needed. 

The  trouble  of  properly  locating  such  a  caisson  is  not  so  great  as 
may  be  imagined.  Any  body  under  water  can  be  moved  with 
much  greater  ease  than  when  above  ground.  While  sinking,  it 
can  be  held  well  in  position  by  ropes  made  fast  at  the  corners 
and  can  be  shifted  by  them  or  moved  around  on  the  bottom  by 
men  in  diving  helmets. 

Our  caisson  is  put  up  in  one  piece,  well  caulked  with  tow  and 
located  upon  the  bottom.  Our  next  move  is  to  form  a  water  tight 
floor  upon  the  bed  rock  inside  the  caisson  walls  to  stop  off  the 
bottom  water  and  allow  us  to  pump  out  the  caisson  and  begin 
the  masonry.  In  order  to  accomplish  this,  we  deposit  a  layer  of 
cement  concrete  only  one  foot  in  depth.  Should  we  bring  our 
flat  boat  alongside  the  caisson  and  shovel  the  concrete  into  the 
caisson — before  reaching  the  bottom — in  passing  through  the 
water,  all  the  cement  would  be  washed  out  and  separated  from 
the  sand  and  broken  stone  forming  the  concrete,  thereby  render- 
ing the  concrete  worthless.  We  therefore  lower  it  by  means  of  a 
box  holding  one  cubic  half  yard,  this  box  having  a  hinged  bottom 


48  RAILWAY     MASONRY. 

whereby  we  can  deposit  the  concrete  immediately  upon  the  bed 
rock  and  in  the  water  so  near  the  bottom  as  to  cause  no  percep- 
tible disintegration.  The  box  being  emptied  quickly  rises 
to  the  surface  to  be  returned  as  before.  We  make  use  of 
strong  concrete  of  one  part  cement  to  one  part  sand,  with 
such  amount  of  broken  stone  a?  can  well  be  incorporated  with  it. 
The  edges  of  tie  caisson  fitting  closely  lo  the  rock,  there  is  in 
consequence  but  little  scouring  out  of  the  concrete.  Not  wishing 
to  injure  it  by  the  disturbance  of  the  pumps  we  let  it  rest  and  in 
three  days  time  it  is  thoroughly  set  and  the  caisson  is  pumped 
dry — when  we  find  the  layer  of  concrete  does  not  present  a  uni- 
form surface  and  is  set  so  hard  that  we  are  compelled  to  point  it 
off  before  commencing  the  laying  of  the  stone  upon  it. 

The  current  seems  to  exert  all  its  force  to  shift  the  caisson, 
weighted  as  it  is  with  the  iron  rails,  and  we  begin  to  realize  the 
danger  in  which  our  pier  would  be  placed  in  time  of  freshet. 
Therefore  we  drill  through  the  layer  of  cement  eighteen  inches 
into  the  bed-rock,  drilling  four  rows  lengthwise  with  tlie  base  of 
the  pier,  and  at  distances  of  four  feet  apart  in  tlie'rows.  In 
these  drill  holes  iron  dowell  pins  four  feet  in  length  are  inserted 
and  leaded,  the  ends  above  the  concrete  layer  which  enter  drill 
holes  in  the  stones  of  the  footing  course  of  the  masonry  being  also 
leaded.  The  cut  shows  the  footings  of  the  pier  and  the  shape  of 
the  work  with  projecting  base  resting  upon  the  footings.  From 
this  base  the  pier  is  built  up  with  a  cutwater  of  smooth,  dressed 
Btone.  well  bonded  into  the  heavy  portion  of  the  pier,  being 
gradually  drawn  in  until  it  is  merged  into  the  pier  at  five  feet 
above  high  water  line  when  both  ends  of  the  pier  are  brought  to 
a  point  in  the  form  of  circular  arcs,  having  a  radius  of  about 
three-fourths  the  width  of  the  pier. 

In   pier  No.  3    the   bottom    lies   upon    the  cropping  out  of 


RAILWAY    MASONRY. 


49 


several  ledges  of  rock,  very  rough  and  broken.  We  here  sink 
a  bottomless  caisson,  whose  lower  edges  we  mast  scribe  to  a  con- 
siderable extent  so  as  to  fit  to  some  degree  the  irregularities  in 
their  surface.  A  diver  must  be  sent  down  to  work  off 
some  of  the  most  prominent  projections  and  fill  up  the  fis- 
sures with  rubble  stone:  but  in  spite  of  all  this  we  cannot  fit  the 
iides  of  our  caisson  closely  to  the  rock.  We  therefore  line  it 
with  canvas  with  a  rather  baggy  bottom,  sink  it  into  position, 
and  deposit  our  concrete  within  the  sack,  which  adapts  itself  suf- 


^c^l 


FLEMISH    BOND— HEADERS   A.STD    STRETCHERS  ALTERNATELY,  IN 
EVERY  COURSE. 

ficiently  well  to  the  surface :  then  we  proceed  as  related  in  the 
case  of  the  second  pier.  This  canvas  bottom  is  a  protection 
for  the  concrete,  as  it  would  otherwise  be  washed  away  by  the 
current  which  would  enter  between  the  caisson  and  the  rocks, 
and  would  scour  out  nearly  if  not  quite  all  of  the  concrete. 

If  there  is  to  be  a  fourth  pier  (not  shown  in  the  cut)  on  a 
bar  of  silt  ten  feet  in  depth,  we  again  use  the  bottomless  caisson, 
which  we  sink  with  rails,  dredge  out  and  put  in  a  canvas  bottom. 
Were  this  island  composed  of  strong  earth  that  would  sustain 
sheet  piling,  we  would  erect  a  timbered  cofferdam,  or  were  the 


3V  RAILWAY    MASONRY. 

bed  of  silt  only  one-half  so  deep,  we  could  surround  the  site 
with  a  cofferdam  of  clay.  The  second  abutment  of  our  work 
is  to  be  located  in  the  water's  edge  with  a  depth  of  only  three 
feet  to  bed-rock.  A  clay  bank  being  right  at  the  work,  our  cof- 
ferdam is  constructed  of  this.  Two  sluice  boxes  are  put  in  so  that 
the  enclosure  can  be  flooded  with  water  at  any  time  that  a  freshet 
is  apprehended,  and  prevent  any  breach  in  the  dam. 

A  cofferdam  is  an  enclosure  built  around  the  site  of  the  work 
for   the    purpose    of    pumping    it    out    and    keeping    it    dry 


JSNOLISH    BON3>— ONE    COURSE    ENTIRELY    OF    HEADERS',    NEXT 
ENTIRELY  OF  STRETCHERS. 

while  masonry  is  under  way.  It  is  necessary  that  these  en- 
closures be  as  nearly  water-tight  as  possible.  They  are  only 
adapted  to  depths  of  less  than  twenty  feet,  and  the  material  of 
which 'they  are  constructed  must  depend  not  only  upon  the  height 
of  the  dam  required  to  keep  out  the  water,  but  also  on  the  char 
acter  of  the  bottom.  There  are  situations,  as  in  case  of  our  pier. 
No.  4,  where  cofferdams  are  not  advisable,  although  the  depth 
of  excavation  is  not  great.  Very  high  cofferdams  of*  earth  are 
expensive,  considerably  more  so  than  timber  dams,  but  in  slight 
depths  they  are  often  the  best,  cheapest  and  most  expeditlously 


RAILWAY     MASONRY.  51 

constructed.  In  still  water,  less  than  seven  or  eight  feet  deep, 
tarred  canvas  well  weighted  at  the  bottom  will  answer  every 
purpose  if  stretched  tightly  and  secured  to  piling. 

But  the  cofferdam  most  generally  built  is  one  of  either  a  sin- 
gle or  double  row  of  piling,  the  first  piles  being  the  guide  pilea 
driven  in  a  row  at  intervals  of  about  ten  feet.  If  the  depth 
is  not  great  nor  the  current  heavy,  we  may  use  only  one  row  of 
piles:  therefore,  on  each  side  of  these  guide  piles,  at  the  top  and 
as  near  the  bottom  of  the  excavation  as  possible  (see  illustration), 
we  bolt  timber  strips  or  wales,  horizontally,  and  down  between 
these  wales  we  drive  sheet  piling,  each  joint  as  close  to  the  other 


BASE  OF   PIER,  A3  BUU-T  WITHIN  THE  CAISSON. 

as  it  can  be  driven,  so  that  buv.  little  caulking  need  be  done  to 
make  the  joints  water  tight.  Two- inch  plank  is  sufficiently 
heavy  sheet  piling  for  some  situations ;  in  other  instances  square 
timber  of  six  inches  up  to  twelve  in  thickness  may  be  required, 
according  to  the  depth  and  pressure  of  the  water.  But  in  works 
of  any  consequence  a  double  row  of  such  piling  is  better,  set 
with  a  width  of  at  least  one  foot  vacant  space  between,  which 
we  fill  and  ram  down  as  it  is  being  filled,  with  a  well-worked 
mixture  of  wet  clay  and  gravel,  which  is  better  and  forms  a  more 
impermeable  filling  than  clay  alone.  The  depth  to  which  these 
piles  must  be  driven  is  only  so  much  below  the  bottom  of  the 
work  as  will  give  them  power  to  stand  perpendicularly  until 


52  RAILWAY  MASONRY. 

the  work  is  braced  from  the  top— and  also  to  prevent  them  from 
being  pressed  in  at  the  foot  by  the  head  of  water  and  soil.  I 
have  seen  cases  where  a  driving  home  of  only  three  feet  proved 
an  excellent  dam,  which  withstood  a  head  of  water  of  seven  feet, 
although  I  wish  it  remembered  that  the  tops  of  piles  were  braced 
from  the  inside. 

But  these  piling  dams  cannot  always  be  used,  it  being  as  impossi- 
ble to  obtain  a  foothold  for  them  in  soft  mud.  as  it  would  be  on 
rock  bottom.  So  there  are  then  two  situations  where  piling  is  of 
no  advantage.  If  the  depth  is  too  great  for  a  clay  dam,  the  only 
other  resort  is  to  make  the  dam  of  narrow  bottomless  caissons, 
sink  them  in  a  line  around  the  site  of  the  work  and  fill  them  up 
with  puddled  clay  and  gravel ;  but  rather  than  do  this  most 
builders  wouki  prefer  some  other  plan  of  work.  Cofferdams 
must  be  adapted  in  strength  to  the  bead  of  water  and  soil  whose 
pressure  they  must  withstand.  Generally  they  must  be  provided 
with  sluices  so  that  they  can  be  filled  with  water  on  the  ap- 
proach of  high  tides  or  freshets,  as  it  is  better  to  pump  the  cof- 
ferdam out  than  to  have  it  washed  away  or  greatly  damaged. 

Cofferdams  can  be  built  upon  rock  bottoms  at  slight  depths  by 
using  iron  rods  instead  of  piles.  These  rods  are  set  into  drill 
holes  in  rows  and  planking  is  laid  between  them.  That  they 
are  expensive  and  not  likely  to  come  into  general  use  can  be  easily 
seen. 

At  great  depths  cofferdams  cannot  be  used ;  neither  can  the  or- 
tlinary  forms  of  caissons  be  used  in  excavations  through  exten- 
sive sand  bars  or  great  beds  of  mud.  There  are  many  rivers,  for 
instance,  the  Arkansas,  which  are  choked  up  with  very  deep  bars 
of  sand,  which  has  been  from  time  immemorial  wasuiug  down 
from  tae  great  plains  and  filling  up  the  original  channel  of  the 
river,  in  many  places  to  a  depth  of  forty  to  sixty  feet ;  indeed  I 


RAILWAY     MASONRY.  53 

think  no  bridge  could  be  built  over  this  stream  south  of  Great 
Bern?,  the  excavation  of  whose  piers  could  be  less  than  thirty 
feet  in  depth  through  coarse  white  sand,  so  loose  that  a  dredging 
boat  could  work  an  entire  year  and  still  not  a  single  cubic  yard 
of  excavation  be  credited  to  its  account,  unless  the  water  was 
at  a  very  low  stage. 

The  Platte  is  a  similar  river,  all  of    whose  bridge  piers  have 
been  put  in  by  the  pneumatic  process,  at  great  expense,  and  in 


PILING  COFFER-DAM. 

Two  rows  of  sheet  piles  (5)  driven  between  horizontal  wales  (a)  which 
are  bolted  to  guide  piles;  c  is  the  clay  puddle  or  filling;  d  is  the 
brace  on  inside  of  work. 

some  instances  with  considerable  loss  of  life.  The  Missouri  and 
Mississippi  are  rivers  whose  deposit  is  not  sand  but  mud.  Upon 
them  also  the  compressed  air  process  is  used,  attended  by  great 
loss  of  life.  On  the  St.  Louis  bridge,  under  a  pressure  of  three 
atmospheres,  several  men  were  paralyzed  or  died,  and  the  working 
hours  per  day  were  gradually  reduced  from  four  hours  to  one. 
Of  this  system  I  know  nothing  from  experience.  I  cannot  treat  of 
it  therefore,  but  will  illustrate  a  sinking  caisson  which  I  have 
used,  and  which  can  be  gradually  sunk  to  any  depth  and  which  ia 


r-4 


RAILWAY     MASONRY. 


eminently  adapted  to  work  in  great  depthsof  mud  or  sand.  The 
only  obstacle  to  its  perfect  working  is  the  encountering  of  a  large 
snag  or  boulder,  but  these  do  not  often  occur  in  actual  practice. 
If  any  doubt  is  entertained,  several  borings  can  be  made  over  the 


I 

site '  of  the  work.  Any  slight  obstruction  need  not  deter  us  in 
the  use  of  this  caisson,  as  the  dredging  chambers  afford  consider- 
able sccpe  for  working:  away  any  small  snag  or  boulder. 

This  caisson  is  made  in  two  portions,  the  bottom  having  of 
course  four  sides,  some  five  to  ten  feet  high,  built  of  timbers  in 
such  shape  as  to  make  the  top  portion  of  each  side  some  three 
to  ten  feet  wide,  from  which  it  tapers  down  to  a  cutting  edge  at 


RAILWAY    MASONRY.  55 

the  bottom,  which  Is  shod  with  iron.  These  four  sides  are 
cut  up  by  the  addition  of  other  walls  built  exactly  the  same.  In 
the  cut  I  divide  the  caisson  lengthwise  into  two  eoual  parts,  then 
transversely  I  divide  it  by  five  partitions  of  similar  construction 
into  altogether  twelve  compartments.  The  bottom  of  the  cais- 
son is  now  ready  for  building  upon  it  the  upper  portion,  the 
outer  sides  being  constructed  as  in  other  forms  of  caissons,  with 
the  exception  that  parallel  to  these  sides,  upon  the  outer  edge  of 
the  head  of  the  wedge  shaped  bottom,  is  built  a  stout  plank  lin- 
iug  extending  up  to  the  top  of  the  caisson,  so  as  to  form  a  hol- 
low wall  around  all  four  of  the  sides.  Up  from  the  heads  of  all 
the  cross  partition  wedges  are  built  hollow  walls  with  perpendic- 
ular sides.  This,  therefore,  gives  us  three  long  compartments — 
two  at  the  ends,  and  ten  cross  sections,  whose  bottoms  are  the 
timber  heads  of  the  wedge  shaped  sides  and  partitions.  In  the 
intervening  space  of  the  interior  of  the  caisson  we  have  twelve 
other  chambers  which  are  entirely  open  at  the  bottom  and  whose 
sides  are  perpendicular  in  the  upper  portion.  After  that,  in  the 
lower  portion,  the  sides  flare  open  towards  the  bottom  cr  mouth, 
this  flaring  shape  being  given  by  the  wedge  shaped  sides  and 
cross  sections. 

When  all  is  ready  the  caisson  is  located  over  its  site  and  the 
compartments  within  the  hollow  walls  are  filled  with  concrete, 
timbers  being  laid  in  lengthwise  with  each  wall  every  six  feet, 
so  that  those  in  the  transverse  sections  will  cross  over  those 
in  the  lateral  walls  anil  bind  the  various  columns  of  concrete  to- 
gether. As  the  concrete  filling  takes  place  the  edges  of  the 
caisson  bottom  cut  into  the  soil  and  the  work  continues  to 
sink  until  some  little  time  after  all  the  closed  chambers  are  full 
of  concrete.  The  caisson  can  now  be  weighted  with  rails 
and  sunk  still  deeper,  or  we  can  at  once  commence  dredging 


56  RAILWAY     MASONRY. 

through  the  chambers  which  had  no  bottoms  and  wt'.ch  were  de- 
signed as  dredging  shafts.  As  the  caisson  sank  from  the  weight 
of  the  concrete,  the  wedge  shaped  sides  to  the  mouth  of  each 
chamber  pressed  the  soil  in  towards  its  center  and  on  up  the  per- 
pendicular shaft.  A  caisson,  say  forty  feet  only  In  length,  with 
fifteen  chambers  of  concrete,  each  chamber  being  five  feet  in 
width,  must  cleave  the  mud  or  sand  through  which  it  passes  to 
considerable  extent,  when  we  reflect  that  the  twelve  dredging 


SINKING  CAISSON. 
L.O  irer  section,  showing  dredging  chambers  and  concrete  compartments. 

chambers  not  nearly  so  large  as  the  concrete  compartments  re- 
ceive into  their  funnel  shaped  mouths  and  for  some  distance  up 
each  dredging  shaft  all  the  soil  that  was  under  the  entire  caisson. 
This  it  does  and  brings  it  into  easy  reach  of  the  dredger.  In 
such  a  caisson  the  builder  can  proportion  it  to  suit  himself.  He 
must  have  sufficient  storage  room  for  such  amount  of  concrete 
as  will  weight  the  caisson,  so  that  it  will  sink  as  the  dredging 
goes  on.  He  must  allow  in  the  dredging  chambers  ample  scope 
for  the  dredger  to  operate.  He  must  weight  the  caisson  with 
the  concrete  so  that  it  sinks  evenly,  and  in  the  dredging  take  the 
same  care  and  try  to  sink  the  work  as  uniformly  as  possible. 
When  the  bottom  is  reached  and  the  chambers  all  dredged  out 
they  should  be  filled  with  concrete  to  the  top,  level  in  all  the 
compartments,  when  the  masonry  should  be  started  thereon. 


RAILWAY     MASONRY.  57 


CHAPTER  VIII. 

CONCRETE  WORK. 

Along  the  lines  of  some  railways,  procuring  stone  suitable 
for  the  general  purposes  of  railway  masonry  is  attended  with 
so  much  difficulty  as  often  to  render  its  use  practically  impos- 
sible,— but  sand,  gravel  or  rough  stone  is  more  or  less  abund- 
ant in  every  locality — and  either  of  these  or  all  three,  combined 
with  the  proper  proportions  of  hydraulic  cement  and  water,  well 
incorporated  with  each  other,  can  be  used  as  a  substitute  for 
stone  work  and  can  be  run  into  timber  moulds  or  frame  work 
and  adapted  to  all  forms  of  masonry  construction  with  success. 

The  excellence  of  concrete  depends  greatly  upon  the  materials 
which  are  used  in  its  composition  in  combination  with  the  cement. 
Sanol  can  be  used  alone,  but  as  the  proportion  of  this  should  not 
exceed  three  parts  to  one  of  cement,  the  bulk  of  the  concrete 
would  be  so  small  that  it  would  be  found  to  be  very  expensive, 
especially  when  fully  as  good,  if  not  better  conglomerate  can  be 
made  by  the  addition  of  at  least  five  parts  of  gravel  or  broken 
stone:  in  fact,  all  that  is  required  is  a  sufficient  quantity  of  the 
bonding  material  (that  is,  the  cement  mortar)  to  unite  the  vari- 
ous particles  of  stone  or  gravel.  The  closer  these  particles  can 
be  made  to  adjust  themselves  the  less  bulk  need  be  occupied  by 
the  bonding  substance  in  order  to  form  a  solid  mass.  Small 
angular  stones  if  pressed  together  will  adjust  themselves  more 
compactly  than  ordinary  rounded  gravel  stones;  but  when  loosel} 
dumped  in  a  heap  the  interstices  among  the  angular  stones  are 
much  larger  than  in  the  gravel — whereas  the  gravel— such  as  is 
often  used  in  roofing — when  tipped  into  a  heap  will  settle  itself 


58  RAILWAY    MASONRY. 

into  as  great  compactness  as  it  is  capable  of.  The  ramming 
of  clean  gravel,  instead  of  being  beneficial,  tends  to  displace  the 
various  members  without  bringing  them  into  more  compact  re- 
lation. If  we  use  for  bulk  neither  gravel  nor  broken  stone  but 
shingle  stone,  which,  as  its  name  implies,  is  in  flat,  thin  pieces, 
and  being  neither  angular  nor  rounded,  can  be  packed  with  con- 
siderable advantage  as  the  mass  of  concrete  is  being  put  into  the 
moulds.  Concrete  walls  in  buildings  possess  one  great  advantage 
over  either  brick  or  stone  in  being  more  porous  than  either  of  these 
and  a  very  poor  conductor  of  heat  or  cold.  They  show  no  frost 
on  the  inside  in  the  winter  and  are  drier  and  cooler  in  the  sum- 
mer. In  ordinary  building  the  concrete  walls  should  be  of  some- 
what less  thickness  than  brick  walls,  and  far  less  than  stone.  I 


CONCRETE  ABUTMENT,  FACKD  WITH  CUT  STONE. 

here  introduce  an  illustration  of  an  abutment  proper,  not  a  mere 
shore  pier,  but  a  work  that  actually  abuts  upon  the  embankment 
and  not  only  upholds  the  superstructure,  which  a  shore  pier  does, 
but  also  acts  as  a  retaining  wall  in  supporting  the  embankment 
head,  which  a  shore  pier  does  not  do.  This  work  is  faced  with 
cut  stone,  although  concrete,  moulded  into  blocks  would  answer 
equally  well.  The  courses  of  cut  stone  were  laid  up  only  one  or 
two  in  advance  of  the  concrete  backing, — this  stone  facing  there- 


RAILWAY     MASONRY.  59 

lore  acting  as  a  mould  for  the  concrete— rendering  timber  shut- 
ters or  frames  unnecessary.  The  excavation  for  the  foundation 
was  made  with  a  level  floor,  into  which  huge  saw-teeth  cuttings 
were  made — so  as  to  more  fully  insure  the  stability  of  the  abut- 
ment and  its  power  to  withstand  the  heavy  outward  pressure  of 
the  embankment, — for  while  concrete  is  header  than  earth  and 
less  liable  to  slip  when  used  in  retaining  walls  or  embankments, 
yet  in  no  case  will  its  weight  equal  the  same  bulk  of  stone  similar 
to  that  of  which  it  is  partly  composed.  Concrete  varies  in  weight 
according  to  the  density  of  the  stone  which  enters  into  it,  120 
Ibs.  per  cubic  foot  being  about  a  fair  average,  while  96  Ibs.  is  a 
large  allowance  for  earth.  Its  value  as  a  material  for  retaining 
earth  embankment  is  therefore  readily  seen.  But  When  we 
compare  it  with  basalt  weighing  180  Ibs.,  or  granite  weighing 
165  Ibs.  to  the  cubic  foot,  ample  reason  can  be  seen  for  the  in- 
creased bulk  which  concrete  must  occupy  in  order  to  resist  as 
much  pressure  as  the  same  weight  in  solid  stonework.  The  pre- 
cautions shown  by  the  shape  of  the  work  are  therefore  explained. 
I  have  already  dwelt  upon  the  making  of  concrete  and  the  care 
that  must  be  taken  not  to  separate  the  cementing  substance 
from  the  other  ingredients  by  dumping  from  any  splashing  height 
or  through  water.  There  may  be  some  occasions  where  honey- 
comb concrete  work  can  be  used,  i.e.,  where  larger  sized  broken 
stone  is  used  and  only  enough  mortar  mixed  in  to  coat  the  various 
stones  over  and  cause  them  to  adhere  whenever  they  come  in  con- 
tact, leaving  many  interstices  between ;  but  generally  solid  work  is 
preferable  in  building  these  abutments.  Instead  of  filling  up  the 
mould  at  one  time,  and  as  quickly  as  possible,  I  put  it  up  in 
successive  layers  of  equal  height  with  the  courses  of  cut  stone 
in  the  facing,  my  object  in  depositing  the  concrete  in  layers  be- 
ing that  in  case  the  bottom  upon  which  it  is  laid  should  settle, 


60  RAILWAY     MASONRY. 

only  such  layers  as  were  already  in  the  work  would  settle  with 
it.  Any  extensive  settling  would  result  in  cracking  the  concrete 
then  in  the  work.  If  the  entire  mass  were  in  position  at  the 
time  of  such  settling,  a  fissure  or  fissures  would  be  noticeable  ex- 
tending from  the  bottom  to  the  finish,  or  nearly  so,  being  of 
course  greater  in  width  at  the  bottom.  This  would  probably  sep- 
arate the  concrete  into  several  distinct  parts  utterly  without 
bond,  thus  weakening  the  work.  But  some  one  may  remark  that 
the  same  settling  might  occur  in  the  other  mode,  and  that  it 
would  not  be  apt  to  take  place  until  considerable  weight  of  con- 
crete had  been  used:  all  of  which  is  true.  But  should  the  set- 
tling occur  when  nearly  all  the  layers  had  been  run  in,  at  least 
the  upper  portion  of  the  fissures  could  be  filled  with  thin  mor- 
tar, called  grout,  and  the  next  layer  of  concrete  would  adapt  it- 
self to  the  depression  of  the  main  bulk.  Again,  in  layer  work 
these  fissures  are  not  perpendicular,  but  zig-zag,  somewhat  sim- 
ilar tq  the  same  in  stone  work,  the  bond  being  still  preserved 
but  lacking  cohesion.  In  heavy  work,  which  depends  greatly 
upon  its  weight  as  a  power  of  resistance,  nr  great  injury  ensues, 
but  in  a  light  wall  depending  more  upon  remaining  perpendicu- 
lar, the  impairment  of  its  strength  by  such  cracks  often  results 
disastrously. 

No  matter  how  carefully  foundations  are  prepared,  something 
of  this  kind  may  occur  now  and  then ;  the  bottom  may  not  pre- 
sent a  uniform  degree  of  compress.'bility.  Especially  is  this  no- 
ticeable in  repair  wotk.  For  instance,  old  work  being  torn  out 
and  enlarged  work  put  in,  the  extension,  resting  upon  a  new  bot- 
tom, is  more  liable  to  settle  than  is  that  portion  formerly  weighted 
and  compressed  by  the  old  work.  In  building  with  concrete  any 
carpenter  would  easily  understand  the  mode  of  putting  up  stand- 
ards in  which  the  plank  framing  can  be  inserted  and  from  which 


RAILWAY     MASONRY.  61 

it  can  be  removed.  The  bed  for  concrete  may  be  upon  timber, 
or  in  case  of  a  floor,  well  rolled  gravel  is  proper,  although  in  any 
pavement  or  floor  great  pains  must  be  taken  in  preparing  the  bot- 
tom, or  the  work  will  certainly  crack. 

I  will  not  undertake  to  explain  this  subject  farther.  The  princi- 
ples remain  the  xsame,  whether  a  tank,  cistern,  abutment  or  ordi- 
nary wall  is  to  be  constructed. 


RAILWAY   MASONRY. 


CHAPTER  IX. 

PROTECTION  AGAINST  SCOUR. 

The  banks  and  beds  of  some  streams  are  composed  of  soils 
very  susceptible  to  scour  by  the  current.  Especially  is  this  the 
case  where  the  material  is  loamy  earth  or  sand,  these  beds  being 
often  of  such  depth  that  there  seems  almost  no  limit  to  their 
washing  out.  Owing  to  the  eddies  and  whirlpools  created  by 


PIER  PROTECTED  BY  CRIB  WORK. 

such  obstructions  as  piers,  the  greatest  scour  can  be  anticipated 
directly  at  and  around  the  base  of  the  pier.  The  only  inexpen- 
sive method  of  protection  in  such  a  case  is  to  deposit  a  heavy 
layer  of  large  boulders  all  around  the  pier.  In  most  instances 
this  will  suffice,  but  should  the  current  be  very  strong,  these 
loose  boulders  will  quite  probably  be  washed  down  the  stream 
again,  leaving  the  masonry  exposed.  The  only  remedy  then  is  to 
crib  up  a  certain  space  around  the  pier  with  heavy  logs  and  fill  it 


RAILWAY    MASONRY.  63 

with  boulders  or  a  very  heavy  bed  of  concrete.  The  latter  plan 
is  the  most  effective  of  all,  but  an  apron  of  concrete  three  or  four 
feet  in  depth  is  a  very  expensive  affair,  equalling  in  cost  a 
like  superficial  area  of  the  bridge  above  it.  Unless  absolutely 
required  to  clear  the  channel,  piles  which  have  been  driven  around 
the  site  of  a  pier  should  never  be  drawn.  It  is  better  by  far  to 
allow  them  to  remain  and  fill  up  any  vacant  space  with  rip-rap, 
the  drawing  of  a  pile  leaving  a  cavity  as  dangerous  as  any  exea- 


PIER  WITH  APRON  OF  HAND  LAID  RIP-RAP. 

ration.  In  some  cases  the  pier  can  be  protected  from  scour  by 
driving  piles  around  it  and  filling  the  space  with  rip-rap.  If  no 
large  stones  are  available,  a  bed  of  broken  stone  can  be  thrown 
around  the  work  and  this  paved  over  with  hand-laid  rip-rap  of 
stones  about  eighteen  inches  or  more  in  depth  when  placed  upon 
their  edges,  as  per  illustration.  This  manner  of  laying  rip-rap 
is  especially  adapted  to  the  banks  of  a  stream. 
If  well  under  water  all  this  work  must  be  done  by  men  in  div- 


64  RAILWAY    MASONRY. 

ing  armor  at  very  high  wages  and  with  several  attendants  to  keep 
the  air  pumps  in  operation  and  to  await  the  signals  of  the  divers. 
The  manufacturers  of  diving  apparatus  charge  extraordinary 
prices  for  very  little,  the  main  part  of  which  can  be  gotten  up  in 
any  company's  shops  at  very  small  expense  comparatively. 

I  hardly  think  it  advisable  to  give  any  directions  or  illustrations 
concerning  the  making  of  diving  outfits.  I  unfortunately  got 
up  an  experimental  suit  once  upon  a  time  and  as  a  result  had  to 
make  constant  use  of  it  for  twelve  days,  and  found  it  anything 
but  agreeable  for  an  amateur.  It  is  one  of  those  cases  where 
"  'tis  folly  to  be  wise,"  and  where  the  masons  can  step  aside  and 
allow  the  professional  diver  full  scope  for  the  exercise  of  his 
ability.  However,  should  any  of  my  readers  feel  very  much  dis- 
posed to  do  a  little  deep  water  work,  I  will  cheerfully  furnish 
them  all  necessary  information  free  of  charge  and  wish  them  all 
success  in  their  undertaking. 

In  concluding  these  articles  on  bridge  foundations  and  masonry 
I  will  only  mention  the  necessity  for  carefully  judging  the  proper 
mode  of  founding,  which  must  depend  upon  the  nature  and  depth 
of  the  bed  of  the  stream.  I  have  endeavored  to  outline  the  prin- 
cipal methods  of  providing  foundations  and  protecting  them,  but 
in  the  rush  of  active  work  I  have  found  but  little  time  to  enter 
into  details  as  freely  as  I  could  wish.  Experience  is  the  great 
teacher,  and  it  will  furnish  all  the  minor  information  which  I  have 
overlooked,  ar.d  aleo  much  which  I  have  vet  to  learn. 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


1914 

6)an'62LU 
D  LD 

DEC  10  1961 


30m-6,'14 


It 3 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


